Let's set the physical age/size to about 8-10. The chronological age is more of a question.

Cosmetics can be up to you. Like the skin can be light, dark, striped, camo pattern...

How do you want to handle gender? Boy, Girl, or genderless (apparently female in pre-pubescent state)? The sex of the character won't be important in the early stages of the scenario. It is really player preference.

At some points I will present a question in the form of a challenge. How the character attempts to handle the situation will determine an aspect of the character stats. Like how some computer games handle character creation.