I love filling out character sheets. I write them on big index cards that I keep handy and alphabetized, so I can always go back and check a character's eye color or DOB. The sheet I'm using now includes all the stuff I like to keep track of, plus the long-standing Dungeons & Dragons abilities to give me an idea of my characters' strengths and weaknesses:
Name: [including nicknames]
Actor I would cast in the part: [I love 'casting' my characters.]
Race: [this can be broad, as in 'human' or 'orc,' or more narrow, as in 'human: Native American.']
ABILITIES [Usually range from 1 to 18]
Secret: See this post.
[Anything not covered above]
This character sheet is working for me at the moment--but I'm sure I'll keep adjusting it!