A short time into our interview, Bria Vinaite starts to cry. It’s a bit of a shock, but her tears last only a couple of seconds, and come not because she’s sad, but because she’s happy. She’s explaining how much she enjoyed making The Florida Project, the wonderful new film by Sean Baker – a film which, if the world is wise, will make her, and the rest of the cast, into bona fide stars.

Baker’s last film, Tangerine, was feted for its subject matter (transgender prostitutes in LA), as well as its technique: the whole movie was filmed on an iPhone 5S. The Florida Project, which stars Willem Dafoe, Brooklynn Prince and Vinaite, has had more conventional praise. Already out in the US, it’s been near-universally lauded. “It casts a spell and tells the truth,” said the New York Times; the LA Times called it “raw, exuberant and utterly captivating”. It’s being celebrated for its honesty, its heart and the quality of its acting. And everyone involved, even the long-established Dafoe (there’s been talk of an Oscar), has been catapulted into its little-movie-goes-big spotlight.

Vinaite says: “While I was filming, none of my friends understood the scale of what was happening. I mean, obviously everyone was excited because it’s Sean Baker, it’s Willem Dafoe, it’s these amazing talents. But no one was there with me through filming, no one saw the day to day, no one felt the magic I felt. So when I came back to New York, to my regular life, it was like: ‘Whatever, you were away for the summer, now you’re back’. No one acted like what I did was special. And now it’s a few months later, and my life has changed so much, my entire life. It’s crazy…”

Her eyes start brimming. She laughs as she cries, and says: “It makes me emotional. I never expected any of this to happen.”

“This” means many things. It means the standing ovation the movie won at Cannes (the first time she had seen the completed film). It means the ecstatic reviews, the swishy frocks, the premieres. It means being flown around the world, feted as a striking new talent, meeting celebrities (there are romance rumours about her and Drake: she denies them). Having to put aside her clothing business; to leave her apartment for weeks on end. It means going to London – “London! I always wanted to travel!” – to be interviewed in a hotel room by a journalist from a British newspaper. New experiences, to be gobbled up and celebrated in Vinaite’s own individual style.

I’m used to interviewing American actors. Usually, they are polite but dull. They give as much as is needed, and no more. They arrive poised, leave poised, tell practised anecdotes, appear open but are closed. They act the part of an American actor. Bria Vinaite is not like this. When we first walk into this hotel room – large and swanky in the international style – she immediately takes a photo of one of the walls. It has beautiful dark flock patterns on it, and her pic includes the wall, the sofa in front of it, and the coffee table in front of the sofa. Then she hands her phone to her manager, Thor Bradwell, and says: “Like that!” She darts on to the sofa, and contorts herself into hot-but-also-funny photogenic poses. Like hip-hop Carry On. Bradwell says: “Do you want the table in?” and Vinaite says: “Yes, just like I took it.” He shoots some snaps, before she hops down, takes a quick look and uploads a couple to Instagram. “I know my angles, I know what I’m doing with my phone,” she says to me. Vinaite – campy, cheeky, tattooed, beautiful – is an Instagram queen.

She adjusts her skirt, a teensy leather mini with metal loops studding the hem, checks herself in the mirror. “This skirt is lit!” she says. “But I can’t sit down in it.” She wore it for the photoshoot but the no-sitting problem meant she’d ended up wrapping herself in a black velvet curtain instead. Now she sits down anyway, hoicking the skirt up like a belt. She’s all arms and legs, scrawny and scrawled.

We were talking Instagram, I remind her.

“Yes,” she says. “I feel like I should send them a gift basket, ’cos literally half the people in my life are in my life because of Instagram.” Bradwell is one: he got in touch via the social network, and she chose him as her manager because he made her laugh and he represented other actors she liked, such as Bella Thorne. “Another hot girl,” says Bradwell. “But Bria is very different.”

She is. Thorne is a Disney veteran. Vinaite is new to acting: The Florida Project is her first ever part. And Instagram helped here, too. Baker and his writing collaborator Chris Bergoch had written the screenplay some time ago – before Tangerine came out in 2015 – but it had proved hard to cast. This was mostly because the main character is six years old. The story, which takes place over a single summer, centres on a bold, mischievous girl, Moonee (Prince), her friends, and her young mother, Halley (Vinaite). It details their lives in and around a motel, the Magic Castle, near Disney World in Florida. The colours are hot pink, mint green, bright yellow; everyone wears neon tie-dye and eats soft ice-cream. It looks bright, but The Florida Project is about poverty: the children are having fun but the adults are not, at least not always. Heart-warming and heartbreaking, the film is political simply through its empathy, how it shows us lives we don’t usually see. I loved it.

One of its joys is the acting. The cast is a mix of experience (Dafoe plays Bobby, the motel manager), real people (police officers and social workers are exactly that), and first-time actors: “We don’t call them non-professionals,” says Baker on the phone to me later. “Everyone starts somewhere and this is just their first film.” Anyhow, this mixture makes you realise just how “acted” most films are, how full of setups and reactions that never happen in real life.

After many auditions, Baker knew he’d found the right girl to play Moonee (Prince has been acting since she was two), but Halley proved even more difficult to cast. He’d been searching for months – he tells me he’d considered every female actor between 20 and 24, plus pop stars as well – but nobody was quite right. On Instagram, Vinaite caught his eye. She’d posted a short clip of herself dancing round her back garden in a pink feather boa, with a silly feather crown falling over her head. He checked the rest of her @chronicflowers feed. There she was, smoking a joint, listing things you need to do to make her happy (“Roll me a really fat blunt. Get me food, all the time, even when I say I’m not hungry. And tell me I’m cute.”). Promoting her own fashion line, Chronical Designs, which includes bikinis, hats, socks, T-shirts, all of which encourage heavy marijuana use.

There was something about Vinaite’s carefree silliness, her don’t-give-a-shit attitude that Baker liked. “She was self-deprecating, she had the physicality and rebellious nature…” He got in touch. She had never heard of him, and initially thought he was just another dodgy bloke making comments. Once he convinced her he was genuine, she watched all his films in one day and flew to Miami for an audition.

“I wrote down the dates,” she says. “Sean got in touch on 14 May [2016]. Two weeks later, I did the audition with Brooklynn.” Baker told her that because Halley had had Moonee at a young age, their relationship was more like sisters than parent-child. By the end of the audition, Prince was sitting on her knee and they were singing pop songs together.

Vinaite was in. “On 17 June I moved to Miami!” – to a large hotel, the same one where, in the film, she sells perfume to guests.

For two weeks before the shoot began, she talked to the real-life residents of the Magic Castle and immersed herself in acting classes run by Samantha Quan, Baker’s partner. Early on, she had to imagine a vital, devastating scene that happens towards the end of the film; how Halley would feel in that particular situation.

“I remember lying on this bed,” she says. “Sam was just talking to me and talking to me, and then it just hit me and I lost it. I was hysterical. It really clicked with me what Halley was going through and the situation she was under, and I understood her emotions.”

In the film, Halley is full of charm and vitriol. She doesn’t always make the best choices. “She makes you want to just shake her and be like, ‘What are you doing?’” says Vinaite. “But you have to think about the fact that she is alone. She doesn’t have a family. She doesn’t have anyone. That’s a tough spot to be in. It’s not angry, it’s just being hurt.”

Vinaite is great in the film, though she was very scared when she started: “I was like: ‘What did I get myself into?’ But there was no other option for me than to give it 150%.”

It took a couple of days for her to get used to all the cameras, and all the people watching. Still, she made sure she knew her words – she’s proud that she never fluffed a line, not once – and when required to improvise, as she did when she filmed a night-time swim with Mela Murder, who plays Halley’s friend Ashley, most of her stuff was kept in.

Her relationship with Prince is central to the film, and they remain close. I speak to Prince after I speak to Vinaite. She’s been learning about Anne Boleyn – “Does she have a ghost?” she wonders – and is immensely sweet. She comes from a Christian family, and when I ask about all the swearing Moonee does in the film, she says: “I hear my mom say some words that she isn’t supposed to say, and my dad says a couple too, but not like the very, very bad words. And they always apologise. So I always wanted to say those words to see how it felt. I was really, really excited about cursing, to be honest with you.”

She loves her screen mother: “We had a lot in common and we had these two aliens, Fred and Ed. They’re stuffed animals and we wanna get them together for a play date, maybe a tea party or an alien invasion. My Barbie dolls will be like: ‘Aaaarrrggggh!’”

Despite being, as she puts it, “not a family person”, Vinaite loves Prince too. They FaceTime once a week (Prince lives in Florida).

“I don’t need to have kids because I have her!” she grins. “For me to be on set and have these tiny kids shouting ‘Bria, let’s play Barbies!’, I’m like: ‘OK!’ I don’t have anyone to play with Barbies with, so I’m down with it. Kids bring so much joy and good energy into my life, and that’s necessary when everything around you is so serious. And then they go home at the end of the day – it’s the perfect situation.”

Her own childhood was a mixture of good energy and bad. Born in Lithuania on 10 June 1993, she was brought up by her grandmother in a small village where she knew everyone: “I remember going sledding in the winter, and my grandmother taught me how to ride a bicycle. You could play outside. It was a really free place for a child.”

Her mother had moved to New York when she was small, and when she was just a bit older than Moonee in the film, Bria moved to Bay Ridge, Brooklyn, to join her. She spoke no English. “It was really intense, I had to have ESL – English as a second language – lessons for three years, because I literally just couldn’t communicate, and I’m such a social person, so it was hard for me.”

For three years she had no friends. Instead, she read books. “I was so nerdy. I had a system for my books on my shelves, I numbered them one through a hundred. I would put numbers on the bottom of the books. I would write book reports for my mum and read them out. It wasn’t even homework, I just liked doing it!”

Vinaite had a tough time at school, especially when she moved up to middle school. “I’m thankful for it in a way, because I learned to fend for myself and not need anyone. I learned how to be myself and not care about judgment from other people.”

She has called out fellow pupils on social media for being mean to her at that time, and, at 14, she rebelled. That was the year she started getting tattoos, and when her mother, now working in finance, sent her to boarding school. She doesn’t like talking about this time. “Once I grew up, I let all that go and moved on with my life. I feel like I blacked out a lot of my childhood. It’s not that it was anything bad that I’m suppressing, but I’m so focused on my future that I don’t think of my childhood, you know? Who cares about that? I’m trying to move forward.”

At 18 she left home, determined not to go to college (“It’s good for others but not for me”) and embarked on her own career. “I had a bunch of different jobs. I worked at a store, I worked at a bar. It’s New York; you have to do a bunch of stuff to get it together.” Her mother was in a new relationship; she has a half-brother, who’s “four or five, I don’t know”. At 19 she started her clothing line. She sold the clothes in head shops and online (she prefers online because she has direct access to her customers and makes more profit). And then, oddly enough, she moved to Miami.

It was winter 2015. New York was freezing – she’d been living near the water and the wind was icy – and when the lease on her flat came up, she and her flatmate decided to up sticks and move “to the closest warmest place”.

Because they had no friends in Miami, they stayed in a lot and worked; their living room was a studio, with sewing machines, mannequins and a heat press machine. The funny Instagram videos started because “I was trying to entertain myself. I literally was at home alone. Just trying to make myself laugh and trying to keep my spirits up, because I was homesick.”

After nine months in Miami, she went back to New York. And then Baker got in touch. “And – whoosh! – everything changed.”

No wonder she cried when she talked about it. Vinaite’s life has transformed. Still, her body is a testament to her previous existence. I ask her to talk me through her tattoos. It’s hard to know where to start: “INFINITY” on her knuckles. “Chief” on one forefinger – “that’s for when I’m smoking” – and a moustache on the other for more smoking laffs. A pair of knuckledusters on her bum (“my first!”). The logos for the LA Lakers and New York Yankees on her hands. And, on her calves, two naked women being attentively sexually serviced by Death.

She has a breastplate of roses with – argh! – a piercing on the bone between her breasts. “I can’t take that one out,” she laughs. “Don’t get pierced when you’re young, folks!”

On her right forearm she has a complicated design to cover over a musical note; she has stars under one ear. So many. And around the back of her thighs, where the top of a stocking would be, she has “Chronical” and “Designs”. There’s no real rhyme or reason to any of them, she says. They were done spontaneously. She might try and “organise” them, get some more roses to cover old ones.

I wonder if any are reminders of people she loves. She wrinkles her nose. “I don’t think I would ever care about a person enough to tattoo them on my body,” she says. “You have to really care, and I just don’t ever want to…”

Vinaite is emotional but not sentimental. Idealistic but pragmatic. Single and happy about it.

“Every girl has the boyfriends they fall in love with and want to be with,” she says, “but I’m a realistic person. There isn’t such a thing as for ever. I don’t want to be married. I don’t want to be tied to the same person for the rest of my life. I want to live my life. I want to travel, I want to work. I’ve seen a lot of women not be able to be their full potential because they have men holding them back, and I never want to be that woman ever in my entire life. I will never put a man first. Like that Harvey Weinstein thing. Hearing those stories made me really upset because I’ve had such an amazing group of men around me. Sean, Willem, Thor, everyone. I can’t imagine being in this industry and having to deal with that, on top of everything else.”

What’s different about Vinaite, I realise, is that she’s playing her own game. Not her mother’s, not a man’s, not Hollywood’s. Though she has a manager now, she’s self-motivated and self-made, on every level. She took full advantage of her lucky break, emotionally and career-wise; she’s determined to continue. And there’s no reason why she shouldn’t, says Baker.

“Every one of the actors now on top of their game started somewhere,” he says. “Bria happened to start with us. She has the knack and she has the acting bug. There’s no reason why she can’t have a great future.”

“I’m all about the future,” she says to me. “I definitely want to keep working on things that make you feel. So many things are thoughtless, and you’ll watch them, and it’s just a distraction. But I want to make work that I’m proud of. I want to make work that makes people talk, that inspires people. I got so blessed with my first project being so special, and now I understand what that magic feels like, I want to do things that make me feel those same emotions again.

“When I’m older, I hope I have a really nice body of work that I’m proud of, and I hope that it’s all films that are impactful, and make a difference. I want to open the world’s eyes in many ways, and I hope I look back and I’m really proud of all the choices I make.”

Ahhhhh, Bria Vinaite deserves all of this and more. I really hope she gets it.

The Florida Project is out on 10 November