When you come to a question as you write, don't settle for the first thing that comes to mind. Instead, get in touch with your inner obnoxious child and ask yourself, "Why?" after you answer your question at least five times. I actually learned about this technique while tracing the root cause of failures in engineered systems. In that context, studies showed that asking why five times really did get to the original failure. The people that you write about are likely more complicated than an engineered system, so asking why five times won't get you to the Ultimate Answer to Life, the Universe, and Everything, but it's a great way to get beyond the superficialities to the deeper matters that will make your story come alive.
If you'd like to know a bit more, I recently posted a note about the five whys on my blog.
Deren, this is one of those simple but extremely helpful tips. Asking "why" again and again is one of the best ways to avoid going in a direction that is expected or cliche. Thanks for another great tip!