Family:
More depth. Does the character have any relatives? Parents? Siblings? Orphan? Do they live alone or with family? You know the drill.

School:
Where does he or she go to school? Are they even in school? What grade level or how much education have they received?

Fears:
I've found the Phobia List to be very useful here and tend ot use it a lot.

Foods and Subjects:
There are many reasons that could make a person like or not like a food and subject. Sometimes it helps to explain why this is as it adds more depth to your character.

The Other Stuff:
There's no real reason for a lot of the things in this bio save for adding depth to the character.

Example:
To continue using Sailorma'at as an example:
Talents: Reading and debating
Fears: going blind
Dislikes: She most definitely does not like people who are afraid to express themselves, seeing them as weak. She can’t stand being cold. She doesn’t like people who are always gloomy or Gothy people. She’s also allergic to cherries and cherry blossoms.
Likes/Hobbies: Reading and debating. She likes to argue with people because it helps her learn about how people think. She likes to read because of the same reason. Her tastes include a wide variety of topics.
Favorite Food: Fried rice, spring rolls, teas
Least Favorite Food: pizza
Favorite School Subject: history
Least Favorite Subject: the sciences
Favorite Gemstone: lapis lazuli
Favorite Color: teal
Favorite Mythological Animal: sphinx
Favorite Animal: birds
Favorite Flower: blue rose
Least Favorite Flower: cherry blossom
Strengths: Will listen to all sides of an argument before making a decision on something. She’s very knowledgeable about a lot of things. She’s good at faking that she can see better than she really can. She’s very stubborn.
Weaknesses: Her dependence on her glasses. She’s very highly opinionated. Doesn’t like to ask for help. Is extremely shy around boys
History: Kougi lives with both her parents and her older brother named Shogo. Her father’s law firm opened a new branch in Elysium Valley and he got transferred there, so the whole family moved from their condo in Yokohama to a decent sized house in the Ambrosia Heights Housing District. She goes to Elysium Valley High school and is looking forward to graduation. She has no dreams about being a senshi and no urge to be anything but who she is. She hopes to win a scholarship to the university in Tokyo and become a lawyer like her father. She doesn’t believe in organized religion of any kind.
As a student, she’s getting good grades, but it bores her. Her heart wants more out of life. Her favorite subject in school is history. In order to keep the mistakes of the past from happening, she strives to have a broader knowledge of the past to safeguard the future.