Here are a few more tips on character building...
(1) Don't make your characters perfect. They have to have a flaw. The story will be too unrealistic if your characters are perfect. For example, I have a character named Honor. He's captain of the guard(called Draedenai in my book), and he is great at making strategies...but...he has this habit of constantly twirling his dagger around and around in his hand. Now, I had no intention of this habit showing up, but nevertheless, Honor won't quit spinning his dagger around, and in the end, it stuck with him.
(2)Start simple--perhaps you've thought of a cool name--write out a short description and maybe one prominent character trait...then let he/she/it develop as they want to.
(3)A character must grow, change, and mature--I guarantee it--no character you create will stay the way they started.
Now, this goes along with my first point. It is a quote by Madeleine L'Engle...
"The hero has great flaws, and the villain has a heart."
Quite cool to think about, isn't it?