Love the composition on this: it's cut just right. Man, I wish I could draw hands as well as this. I can't draw hands at all!
Colors are fun, just watch your lighting: where is it coming from? Also a light can be cold or warm so you should choose your color according to that (for example, the blue on her hair makes it seem like there's a cold light source coming from the right but on the left side of the nose, it seems likes there's another warm light source somewhat contradicting the first one.. it's not easy to explain, hope it's okay). I sometimes like to note on the paper where my light(s) are coming from so I don't contradict myself