I thought I'd show you a bit of the behind the scenes of the illo from my last post.
You can see the sketch here.
I paint in acrylics. Here you can see the underpainting in a purplish blue.
I paint over that in thin washes.
When it's all done, I outline it using various colors of Pitt Artist's brush pens. Then it's into Photoshop for some fixes, enhancements, & assembly, if needed. I usually paint different elements on separate layers, then assemble it digitally, but for this I didn't think it was necessary.