Sketch, inking, masking (part 1), masking (part 2), partially completed flat colouring, and fully completed flat colouring!
In the inking and masking stage, you can see how the inking lines overlap. They're on separate layers, but I do the inking behind the areas that will be eventually covered up to make flat coloring and shading later on easier! I use the ink lines to select areas I want to work on. If I didn't do the inking behind the characters, for example, my selection would bleed into other parts of the drawing!