A character should be more than the sum of its quirks.
A character should reveal elements of personality through interaction with other characters,not just because the author tells you that s/he has certain traits.
A character has motivation, something s/he wants (or at the least something s/he doesn't want: "I'll never go hungry again!")
A character has a world view which informs the way s/he observes and relates to the world around her.
A character has a physical appearance, of course, and it's usually worth describing(although not in a lump paragraph) -- but only in a rare few cases will that appearance be the most important thing about him.
Characters don't only see and hear, they also experience the world through taste,smell, and touch.
We cast shadows when we walk outside on a sunny day. So should the characters we write.
HOW MUCH OF A LIFE?