How Do I Know What I Think Until I See What I Say?

Agent Nathan Bransford posted a blog entry recently about figuring out what your characters want , and I have to say that this is the thing that I find lacking in a lot of things I read, especially YA. Because there are so many conflicts inherent in a teenager's every day life -- school demands, and cliques, and parental demands, and Big Emotional Milestones -- sometimes what the characters actually want gets lost in the noise of the plot and doesn't come across clearly. But it's not enough for things to happen to a character--the character has to want certain things and try to make certain things happen, and then react when they do (or don't). Since I'm at the beginning of about seven SQUILLION projects right now, I'm figuring out what motivates my characters. This always happens for me in layers, like so*: 1. The superficial motivation. When I first find a character, I already know something of what motivates him or her. That's how they come to me.