When I arrive to interview Marianna Palka in an Edinburgh hotel, the first surprise of the day is that she hails from Glasgow. "I don't look very Scottish," she concedes, with a giggle. "If I had red hair, then maybe." In fact, it's blonde, a colouring that perfectly complements her tanned skin, brown eyes and athletic figure. My wayward detective work isn't helped by Palka's surname (she is three-quarters Polish, with Scottish blood on her father's side). But what really threw me was watching her Los Angeles-set directorial debut, Good Dick, in which she plays the lead with a flawless American accent.

With the 26-year-old Palka having lived in the US for the past 11 years, as you might expect the film is heavily influenced by the world of American independent cinema. The story of a tentative relationship between an emotionally damaged woman (played by Palka) and a video rental clerk (Jason Ritter), the obvious comparison is Kevin Smith's no-budget breakthrough Clerks - not least because both Palka and Smith were forced to shoot in their real-life store settings at night. "Ugh!" she says, rolling her eyes when I bring up Clerks. Had she heard that before? "Yeah, I have actually. I mean, a couple of times, I suppose."

Perhaps invoking Smith's name is something of an insult: after all, her parents force-fed her a diet of hardcore European art-house cinema when she was young - in particular the work of Polish maestro Krzysztof Kieslowski. Living in the West End of Glasgow, Palka was given a firm introduction to the arts by her parents when they weren't busy running a wholesale bag company, Ralka Bags, to make ends meet. "They funded a lot of art - they'd bring over all these theatre groups during the Edinburgh Festival. They'd stay with us. So I'd see all these artists in my house. They were all sitting up straight and had nice muscles - and were very nice people. So I was like, I want to do that!'"

Right around this time, Palka saw Ken Loach's My Name Is Joe, and was so inspired by the lead performance by Peter Mullan, she wrote him a letter. The actor wrote back, and he has since become a friend and mentor to Palka. "I think he'd probably be like, We're just friends'," she says, a little uncomfortably. "He'd be very humble about it. But he changed my life when I was younger, and was very, very nice to me. He really told me what was a good film and what wasn't."

Shortly afterwards, Palka headed to New York to study at the Atlantic Theatre Company, though she had a back-up plan. "I thought, If New York doesn't work out, I'm going to go teach tourists how to scuba dive in the Maldives'."

Fortunately, it did work out for Palka - though, by her own admission, when she started attending classes, she stuck out. "I was straight off the boat from Scotland. My hair was really short and I was very loud. I was different to the other students." It was there that she met Ritter, who was a year above her. They swiftly got "close", becoming a couple and later forming a production company, Morning Knight. With her partner the son of Three's Company star John Ritter, Palka calls him "a really unique actor", something that will certainly be put to the test when he appears as Jeb Bush in Oliver Stone's forthcoming presidential satire W.

Aside from Ritter, Palka gathered around her a group of up-and-coming actors and film-makers to help out on Good Dick. There's a blink-and-you'll-miss-it cameo from The Village star - and daughter to director Ron - Bryce Dallas Howard. In addition, Mark Webber, rising indie actor from such films as Storytelling and Broken Flowers, plays one of the store clerks. "We're like this community of guerrilla film-makers," Palka says. "It's really, for me, about how to be happy. I think when you have friends, who you respect, and will tell you the truth about your work, and whose opinion you really want, then that's part of staying happy."

Palka knew both Webber and Howard from her time in New York because "Los Angeles is kind of isolated", as she puts it. While Palka now lives there, coming back home to Glasgow twice a year, she admits it's not an easy place to exist in.

"There's an anonymity to being in Los Angeles which is very specific. People feel like there's not the sense of belonging." It's why, in part, she decided not to name either of Good Dick's two lead characters, something that only really dawns on the viewer when you glimpse the end credits and see blank spaces next to her and Ritter's names. "I like the dynamic that you didn't really know them, that they could just be somebody that you pass on the street."

Much of the story is taken up with the painful courtship between Ritter's character and Palka's. He tries to get into her life and she pushes him away with a barrage of abuse - again and again, to the point where you begin to wonder why he still bothers. "I think that he really loves her," reasons Palka. "Again, he really sees in her something that other people wouldn't, which is sort of the definition of being in love with somebody. I used to talk to Jason about how he was a knight - fighting a dragon. And she was the damsel in distress, but she was also the dragon. So it was really interesting. We always tracked where we were. Who was he fighting? Her or the dragon? And how was he doing? I think that helped us keep track of where the relationship was."

Still, it's a delicate balancing act that Palka - as actress and writer-director - must pull off. Compared with Ritter's puppy-dog enthusiasm, her character is the ultimate ice-queen. "I think what's interesting about her as a character is that there is a grain of hope, even in the beginning. She's closed but she has a little tiny opening. And I think it gets bigger and bigger - albeit in small increments. That's basically what keeps you afloat through the film. Otherwise, just watching someone who's closed or depressed can be a bit too much. I think I struck a really good balance with how much reality and how much heaviness I had to bring to her."

By comparison to her character, Palka comes across as well-adjusted. Her parents divorced when she was younger and, while her father is now retired, her mother still works in a Glasgow art gallery. Her stepfather is a social worker, and she admits that the mechanics of working a nine-to-five job fascinate her.

"I just think it's brilliant," she gushes. "Every time I'm back in Scotland, I go to sit in the gallery and watch her. She has a lot of grunt work to do, a lot of lifting, moving things and organising people. It's different than planning to make a project then doing it, for 17 days or a month or two months, then spending a year cutting it. That's very different to a nine-to-five job."

Certainly being a filmmaker has incredible highs that more every-day vocations can't match. Like being accepted into Sundance, the festival Mecca for all US independent films. "I didn't think it was going to happen," says Palka. "When we got in, we were in a car. Jason screamed and I was like, Oh, OK'. It was very overwhelming." The festival even made Palka an Annenberg Fellow, and gave her $15,000 to finish the film. Since premiering it there, she and Ritter decided to self-distribute the film in the US. "We didn't come out of Sundance with a big huge offer, so it didn't make sense to give away the rights," she says. "So if you buy the DVD in America, 100% of it goes to the film-makers."

While Palka has a few other scripts she's working on, she's hoping her next gig will be acting alongside Ritter for director Nick Towne, on a film called In Theater. "I'm going to play a Scot, which I'm very excited about," she grins.

It's yet another no-budget project with friends, which seems to suit her down to a tee. "I feel so happy. I feel so happy doing films with my friends and working, and doing things that push me on a personal level. That's really more important to me - that's where my drive is. If I keep doing that, it'll be great. It's been working so far. I feel good about it. I love my job. I just love it."

Good Dick opens on October 3.