I'm currently working on a project that requires a character of a 12-year old girl. The first sketch I did (and submitted) was done in my "signature" kids' style.
While rendering her, I began to think the lines could be simplified. I drew inspiration for the rework from the "Dora the Explorer" character.
I ended up with a final rendering very close to this reworked sketch, but added length to her legs to make her a bit older. I don't suppose she's quite 12 yet... maybe more like 8? But I don't think it matters too much.