I know I've said it before, but I'm going to repeat it. The devil is in the details. Yet, so is the soul of a character. Strange coincidence, no? I'm joking. But I think a person comes alive in the strange eccentricities and habits that people develop in years of life. Why should characters in your stories be any different?
Do you have a character that touches their visor every time they drive through a yellow light? Or refuses to walk over one of those open grates in the sidewalks? How about a female character that refuses to wear anything but underwear from Victoria's Secret? It's these extremely random facts that breathes life into the character, grounds them into something that a reader can understand and potentially relate to.
Here are some more details that you may to consider jotting down when you're working on your next character sketch:
1. Physical imperfection or things that your character might want to change about him or herself: this could affect how your character acts around other, how she/he dresses, confidence levels, etc.
2. Characteristic gestures: a list of these can help when writing as they can be used along with dialogue tags. (ie. running fingers through hair, drumming fingers, rolling eyes, etc.)
3. Personality type, quirks, and eccentricities
4. Bad habits
In a side note, here is a great music video for Weezer's latest song. It contains all the great viral videos that have taken off during the past couple years. Enjoy and have a great weekend.