I'm not really shading anymore, but highlighting. my method is: color the character way darker than usual. THEN, on a new layer above the coloring go over where the highlights should be with yellow. Or orange. Any shade really, just mess with warm colors for a warm pic, cool for a cool one! then mess with the opacity and mode until it looks right, and ta-dah! my new shading. I don't care if you use this technique in your stuff, and tbh I learned most of it from my sister so its not mine anyway
enjoy, even though the stupid oekaki messed up the image by blurring it. It looked much more crisp before...