General Rule: Say a major character's name

Make the dialog say a major character's name as much as you can when he is being introduced. It helps the audience to connect name and face. This is particularly important when your story has a lot of characters, less important if it's a limited cast.

Examples:
- American Gangster: the dialog says "Frank" four times in the first 6 minutes of the film. Then, Richie Robbins is referred to by name, in the dialog, twice within his first thirty seconds of his intro.