OH for the life of a young film maker about to embark on that make or break second movie.

Does one spend the weekend fine tuning the schedule, placing last minute pep calls to the actors, or standing in front of the mirror lip-synching to Eighties pop ballads?

"Gloria Estefan, Debbie Gibson, The Bangles…" recites Craig Johnson, the writer-director of The Skeleton Twins, a new comedy out next week which features a scene in which the two lead characters rock out to a tune from their past. The duo are a brother and sister, played by Kristen Wiig and Bill Hader, reunited after a long period apart.

Speaking before the UK premiere of his film at the Edinburgh International Film Festival in June, Johnson can now laugh about his weekend lost to cheesy pop songs, but it seemed like a crisis at the time.

The original song in the script was Hold On by Wilson Phillips. "Then Bridesmaids came out and had a whole huge thing with Wilson Phillips and that song… I was like, 'Damn it, Bridesmaids, you took my song.' This was before Kristen had anything to do with my movie."

Landing Wiig and Hader was a coup for Johnson and his co-writer, Mark Heyman. Johnson and Heyman were film students at NYU and wanted to write a movie together. Eight long years later, The Skeleton Twins became a reality.

"We knew the kind of movie we wanted to write tonally - bittersweet and funny and emotional - but we didn't know what the subject matter would be. So we just started throwing around ideas."

Keeping ideas warm is a crucial part of being a film maker, says Johnson. Those that won't go away are the ones to look out for.

"If an idea comes back to me three, four, five times, starts expanding, I start seeing a beginning, middle and end, I'll think okay, maybe I should start this."

The Skeleton Twins was such an idea. Involving as much in the way of drama as comedy, casting was going to be crucial in getting the right tone.

On his first feature, True Adolescents, Johnson had worked with the actor, writer and producer Mark Duplass.

"When he stepped in to executive produce he was able to Ninja-kick doors open for us," says Johnson. It was through Duplass that the film landed the much sought-after casting director Avy Kaufman, whose credits include Lincoln, Life of Pi, and Sixth Sense. "The fact that she responded to our little script was a miracle," says Johnson, 38.

The shoot was scheduled to last just 22 days, so the production had to hit the ground sprinting. It helped that Wiig and Hader had worked with each other before, notably on Saturday Night Live. "You can't invent that kind of chemistry, it's there or it's not."

Their performances will be eye-opening to those who only know them from comedy, says Johnson. Then again, he agrees, comics have often been known to make remarkable dramatic actors.

"Most of the funny people I know are also really smart, they're good observers of people and can soak up a lot, so the transition to drama is pretty easy. There's a lot of truth in a lot of comedy, it comes from a dark place, from a sad place, and I think a lot of comedians are really in touch with the darker sides of their lives. There's a whole tradition of comedic actors doing these warm, dramatic roles."

Johnson was born in Seattle, lived in New York for nine years, and now resides in LA. He has a sister with whom he is very close, but their relationship is not the one depicted in the film, he says.

It's not autobiographical. However, relationship dynamics, that play between a brother and a sister, are very much taken from my own relationship with my sister. Specifically, we're very different people but the way that we connect is through a dark, macabre, weird sense of humour."

His sister, a counsellor, has seen the film. Did she recognise any of her ways or lines? "I'm sure there's some stuff in there that she says."

The Skeleton Twins arrived in Edinburgh after a successful premiere at Sundance, where Johnson and Heyman's screenplay won an award. Sundance changed things for Johnson, in that material started coming to him, rather than him having to seek it out.

"Every time I open a script I didn't write I'm on my knees praying that it's good, and it almost never is," he says. "Most scripts aren't that great. They're not terrible. Most of them are 60 per cent there but it's very hard to find that one that just sparks you.

"But there are a few that I have read that I do really like, then you throw your hat in the ring. Often you are one of many people vying for it. I'm new on the scene as a director for some of this."

He has learned to be relaxed about that, though.

"The career of a film maker is like bees in a beehive. Sometimes you are up and buzzing around, sometimes you are down at the bottom. As long as you are continually creating and working on the next thing, that's all film makers care about, trying to get the next movie made."

The Skeleton Twins opens in cinemas on November 7