Help me with character appearance?

Alright B&A, you're probably getting tired of these questions, but help me out here. So I've got this character, Veer Thomas, who lives in a dystopian future where gender roles have been largely flipped and danger is synonymous to recreation. She's a female in her mid-20s and personality-wise is very no-nonsense, task-oriented, and a deductive prodigy. (Think Light Yagami from Death Note or Dr. Cable from Uglies--that sort of character). She's known as one of the most desirable females in her region by sole virtue of the fact that she's impossible to please, and men have turned winning her into a sort of game--she's like the Moby of relationships, so to speak. Anyway, I'm having trouble deciding what she should look like. Usually I have a clear picture of my characters in my mind, but this time, I'm blank! Any ideas are appreciated!! <3