We need to be very careful when we're writing MG or YA that we don't try to view our mc as an adult would. We really need to be IN our MG or YA character's head and see how their adolescent view of the world impacts what we show and how we portray their thoughts.
He gave an example of showing a character sitting at a table in the room where we were gathered. If a woman entered the room and the character at the table noticed she had on red stiletto heels and even what brand of shoe they were, what would that tell us about the character? That she's a woman (or a gay guy into shoes). If the character looked at the woman's chest first, we could assume the character is a guy.
Clint then suggested we consider that the character was a woman who'd given birth to a baby a few weeks ago and was suffering from severe postpartum depression. He asked how differently she might see the room we were in compared to someone who was just happy to be there and whose life was good at that moment.
When we describe what our characters see, it should reflect their life experiences, their current emotional state. What in a busy room draws their attention is important. In fact, it's a great way to show their emotional state without telling the reader what it is.
Clint asked me why my character in the chapter that was being critiqued was acting the way she is. He suggested that if the reason I gave was all there was to her motivation, then she was two dimensional. It really gave me pause. I think I may need to give a little more thought to the internal motivations and finally break down and do up a character bible for each one.
What kind of information do you put together on your characters? Where do you keep it?