It's nice and clean lines and coloring, but the structure and detailing of the figure has some flaws. Anatomically, her head size is a mite too large and her arms are far too skinny. Her torso in general is very small and is about the same size as one of her thighs. Here's a good resource for human anatomy. Of course, since your character is stylized, you won't follow it to the T.
The hair is pretty nice and matches the feel you are going for, but Deviant Art has loads of hair tutorials to look at, including some specifically for anime style drawings.
Your clothing folds are the part the gets me the most, they're too sharp. Try doing some personal studies on folds. Drape a cloth or towel over a chair and draw the folds. Find some references of folds and how they fit to the body and draw those. Then practice simplifying the technique to match your style.
The composting also should be switched up. Avoid drawing your characters straight on, try drawing from 3/4 view, profile or even extreme angles.
Overall, it's a decent piece, but needs some work. Experiment, study, and practice practice practice!