Super cute!!!

If you want a tip about shading;
on another layer over the lines (or under depending on whatever you prefer to do) use the paint tool to fill in the colour of the shadows (try to avoid using black! Colour theory.)
Then erase wherever the light should be! I do it all the time. It works much better than drawing where the shadows are. You can shift the opacity to dictate the intensity of the shadow.

Also, to accent strong lights, use a brighter colour sparingly. Underneath the shadows you can always add a hue effect to control the lighting. (Excessive blues? Overlay a blue tone!)

Hope this helps. B")