Gigantic file ahead! I made a new revision of the old tutorial because I hated it. Though it was funnier. xD Please excuse any grammar or spelling mistakes for I'm not fixing them, and I hope this helps you. <3
This is really wonderful. I like how you modify the color of the original outline. I'm left with a couple of questions, though: what's the purpose of the second layer in the second step? Is that just so you don't accidentally mess up your outline? Also, what do you mean by preserving opacity in the second step?
Yes, the second later is so I can freely color without worrying about mession up the lines. c: And by preserving the opacity, you can't color outside what's already on the layer when you preserved it, so it comes really handy for step 4. If you mean how to preserve the opacity, it would depend on your art program. c: