I agree with the rest, the photo makes it difficult to give good advice (though it's still honest advice). But nevertheless, the tips about the brightness are very good ones, starting with your choice of colors. I'd also say that I'd want to "cut" the size of her eyes, by lowering her upper and raising her lower eyelids just a tad. That would help knock down the "pop-eyed" look. She looks startled.
I remember a tutorial, albeit on painting anime eyes, but the basic techniques and principles are the same. The author, working in the large scales that we find with anime figures, even went so far as to pencil in lightly the outlines of the iris and other colored regions, once he had laid down his eyeball color. If I can find it, I will link it back here.
Prost!
Brad