She looks great! It's such a clean sketch, I'm impressed!
Personally I prefer colored pencils. I just like how it looks when the picture is finished, and it's clean and easy. However, if you prefer to mix your own colors, it's pretty hard to do this with them.
Honestly, with sketches like this, I tend to leave them just like this, as line drawings. But yeah, if I desire color, then colored pencils is the way I go.