I like the idea and the colors you chose fit pretty well, however after seeing your Kakashi and Mileena i cant help but to feel that Natasha was a bit simplified, her boobs are a bit unrealistic and her face is maybe a bit too simple, i personally like your other works a bit more.
Her boots and her style however are really good and i am sure that as you progress Natasha will too and your idea has potential to be awesome.