I think the ear should like... appear a bit more on the head and connect to it. Right now, I think it seems like it's behind the head or something.
With the colouring, hmm... It seems pretty decent overall; most of it seems to be using the same light source.
The shading on the face seems off. On simpler faces like this, I think the shading needs to be used to show the face's/head's structure/shape. What I'd do is make the shading line thinner around the chin and have it gradually become thicker as it goes along the outline of the face, and have the shading on the side to our right, too. Or maybe it shouldn't be on the side to our right because of the light source... Oh, and you stopped the shading on her face outline when it met that curl of hair; it should continue.
I'm not entirely sure about the shading on the hair... I think I'd make most of the hair hanging to our left use the darker colour since it should be behind the body as far as the light source is concerned. The left-most outline of it (which you currently have shaded) could probably be unshaded since it might be hanging out enough to be hit by the light. The hair hanging to our right should maybe have some shading on the side to our left to give it some sense of depth and to make it look like it's on the same angle or whatever.
You should use some grey to shade the white, too. The shading seems incomplete...
I'm no expert on breasts, but here are some observations I've made over the past few weeks or something:

I think the breast to our right could use a bit more of a round shape or something, and maybe be sticking out less. The breast to the left could maybe use a slight outline or maybe just a little start of an outline... Or maybe shading is all you need.