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 SoderberghYou can't get good at anything unless you do it day in and day out, over and over.
Steven SoderberghThe art model of problem solving is incredibly efficient because ideology has no place there.There's only the thing and what the thing needs to be.
Steven Soderbergh