I know what's good for me. I can't play black or gray. I can't be a villain or anything close to one. I have to play white.
Your senses are reeling all the time. Finally you find something to write and the very next day you go out and see something else which totally contradicts what you've written and every conclusion you've come to.
The great thing about films is that you have access to this whole world of experts who teach you the skills your character's supposed to have.