I know not many writers do this, but I highly recommend it! Get to know your characters! I don't mean just figure out what they look like and a general sense of who they are. Get to know them like they're your best friend.
It's like those Facebook questionnaires that I see all the time. "How well do you know me?" It proceeds with a bunch of questions that the best friend/friends/family are supposed to answer about whoever posted it. Do that with your character, except you're writing out things about them.
The best way to do this, besides the questionnaire is write out 21 deep questions and then have every single character answer them. I don't mean simple questions like, "favorite color" unless you can answer it with a LOT of detail. For example:
Favorite color?
Bright pink. The first time I ever saw a pink rose, it was just after a long rain. Gosh, that rain shower must have lasted three whole days. I was feeling down and a bit depressed. However, the first thing I saw when I went outside was that beautiful bright pink rose. It lit up my day and now every time I see bright pink, I think of that rose. Makes me smile.
If you can't answer in that much detail, go ahead and ask deeper questions. Think about any childhood trauma that may have helped turn them into such an angry person. Think about why they have tattoos and the experiences that lead to them. Brainstorm what created their personality and think of questions that can be answered that may help turn that character into a more 3D person. Bring them to life. Think about all their flaws, problems, any phobias, dating patterns, sex life, family problems, etc. Go deep! Really think!
For my screenplays, I really enjoy writing a short story about all of these details for all of my characters before I truly write the script. I want to know them so well that I know exactly what every single one of them are about to do or say.
Turn your characters into your fictional best friends. Then... try to bring all the history of each of them into the story the best you can. The more details you can add into your story, the better!
Hope this helps!
----Alyx----