Start with the general details. Write down your character's name, age, birth place and family background. These details will are able to offer you more information than you think, like your character's accent, social status or way of dressing. Describe your character physically.
Define your character's type. Make a note of your character's place in the film. Determine whether he is protagonist or antagonist, a major or a minor character, a dynamic or a static role. He might be a stereotypical character, a foil, a round or a flat character. If he is a protagonist, then write down the type of hero he portrays. He might be the traditional hero, an anti-hero, a tragic or a romantic hero.
Specify the character's goal. Write down what it is that your character is after and how he goes about it. The goal is your character's conflict and this conflict is what makes him an important part of the film and what moves the story forward. Discuss the obstacles your character faces until he achieves his goal, what he learns and how he matures throughout his seeking.
Talk about your character's relationships. Make a note of how the other characters of the film interact with him, who helps him and who hurts him. Write down who he loves and hates, who he has a soft spot for and who he wants to harm. This will help explain his actions better and make him more realistic as a character.
Define his main fear. Everyone has a fear, and if you want to turn your character into a real person that jumps out of the screen, then you should identify his. Determine his main weakness, as this will help you understand him better.