Run + Step by Step

Step 1 Thumbnail:

Step 2 Clean Pencil:

Step 3: Flat Colors: I picked some colors that go well together (purple-yellow mainly).

Step 4: Start shading, I usually color pick the local color and then pick a darker version.
I set the brush at 50% with pressure sensitivity. Mostly I shade one patch with light pressure, and then go in around the edges with a harder touch.

Step 5: Do the same thing for everything :P I then also pick a lighter shade and might add in some highlights.