Iceburgs

"Drama, instead of telling us the whole of a man's life, must place him in such a situation, tie such a knot, that when it is untied, the whole man is visible."—Leo Tolstoy

Although you need to know your character inside and out, it doesn't take much to reveal a wealth of information. Be cautious of overloading your story with too much backstory. A few well-chosen details can convey a character's history and experience. Write your first draft and include as much backstory as you want. When you edit, follow the iceburg rule for backstory—10% of what you know about your character should be on the page. The rest lends weight and helps you draw your character believably.