The perspective on it is very nice. Although i agree the head is a bit too rounded out. Its really good for starting work with photoshop. The only thing that would make this picture stand out really greatly is adding more shadows and highlights to the hair. Hope this helps. Try this: First put in the darkest color for the hair, then using a color a bit darker than the one you have set as the base color, just streaks will work and it give the hair more of a hair like appearance lol. After that take the burn tool and burn some of the edges but watch out because if you do it too much it can ruin the picture. After that take the doge tool and do random streaks. Experiment with it a lot and you can get many interesting results. : ) Hope this helps.

It is a professional looking image,some mistakes. Some shades are odd added on fingers and some on neck and body, I would like see more shadows at cleavage area because it looks very flat. I would have added one more tone to make the image look more 3D, shade on hair makes head look a bit flat. As for no shades in mouth. I not shoot down the effort of trying which is good. Skin tone is perfect so is cloths. Cute image in overall , worthy submitting.

The way cloths falls is perfect, pose seem prefect, I wonder if you used reference?