I think he gets his inspiration for his characters from friends around him and from movies he watches…he takes out the cool aspects and things he likes to see in a character and blends it and out comes a character.
Once you have this basic profile you put that character in certain settings and ask yourself: what would this character do now? how would he act, etc by doing this you get even more aspects and the character grows and grows…
with jackie brown he was more restricted because of the novel, but he worked that out pretty nice  
