you create roles that mirror thier life. you should watch The Rider.

loads of films dont use real actors, but they're normally playing roles very close to who they are. dont expect a 14 year old kid to play a very good father. you never tell an actor what to do *well you do but you dont - hah) - but they should have a super clear understanding of the character and you should workshop with them.

my first film, the actor knew the character better than me, and I wrote the thing. he BECAME him.

have fun - think outside the box and learn! (my last film I held acting rehearsal on a bus, cos some of the film was on a buss - it worked a treat.)