With such a premium placed on talent, no one can afford to let race determine their decisions. To really confuse you, I think a director needs to be an extremely focused person who is open-minded and imaginative. At the same time she needs this focus, she must also be open-minded enough to see an opportunity to enhance her original idea. You may have read that someone like Hitchcock shotlisted everything beforehand and had the movie edited in his mind before he started shooting. The most important quality that I look for in an actor is a collaborative spirit from the actor.
Some actors are very protective of the image they project.
I find it more fun to work with an actor who isn't as concerned with the image but is willing to take a chance and go out on a limb for a role. It's a lot harder on the actor, and my job then is to go out on a limb with them. Put your actors in cross or back light to the window if it's day. For night, look at the practicals carefully. Use a small camera.