The shading is abit sloppy, try to refrain from dodge/burn tool since it's better to choose the colors and paint it yourself =) You need to be careful arround the edges, the colors are spilling out.
I don't know much (read: anything) about the program, but in general, I'd try and stray from zig-zag lines for highlighting and try to use all lines going the same way, maybe with a bigger brush in a lower opacity.