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.
“I knew you had to go in and audition and maybe they'd hire you, and that's where you start. I had a good understanding about press: that it's the actor's responsibility to publicize his or her films.”