I praticed making faces in the mirror and it would drive my mother crazy. She used to scare me by saying that I was going to see the devil if I kept looking in the mirror. That fascinated me even more, of course.
You want to try and bring a character to life in an honest a way as you possibly can. It doesn't matter whether he's a doctor, an actor, a car salesman or a captain of a starship. If you can bring truth and honesty to that character, then your audience will believe you.

