As said by Tindy you're gonna need more contrast to make details and shading stand out more. As it is now everything kinda blends too much and it's hard to see any sort of detail or shading that might be there. There's that and then the entire chest besides the shoulders lacks any form of shading, and the hair would probably look better if it was moved down a pixel or two(although I'm not positive on this one, it could just be the shape of it, I'd need you to IMGZOOM it so I could taker a closer look).
Overall though it's not too bad for a first try, mine was much worse lol
But try to fix that stuff up and we'll see if it still needs work from there ^_^
Edit: It would also help if you showed us the anime picture you found, it helps to critique if we know what your reference is.