Thought of the day for both directors and writers - what does the character want?
Yes, this is what it's all about. Does not matter what stage you are in; creating the character on paper, writing the treatment, writing the script, rehearsing with the actor or filming - in all of these areas it's about the same thing - GOAL of the character.
You can define or view it any way you like. Their goal, their needs, their desire, all adds up to what they want, which really will define who they are. Yes, actions speak louder than words, so what your character does to achieve his or her goals is all important.
So as the writer, you must create solid goals, needs, wants.
As the director, you must be clear on what the character wants, as knowing this will inform you how to rehearse and direct the actors. It's all about what we want in life, so it's the same in cinema.