My experience over the years with working with people who are not actors or not trained actors is that you have to get to know them well enough to see what they have that's translatable onto the screen. So you're constantly calibrating to play to their strengths. And the key is to never ask them to do things that are beyond their abilities or are really far away from who they are at their core.
Steven SoderberghWhen things go right it's hard to figure out why, but when things go wrong it's really easy.
Steven SoderberghEvery time you make something that somebody likes, your impulse is to remind them that if you hadn't made some of these other things that they hated, you wouldn't have been able to make the thing that they liked.
Steven Soderbergh