try adding more contrast. you could do this by making a new layer with burn and filling it with various colors until you find something you like (or try other layer blending modes).
thanks peoples - Cello, I did try to mess with contrast using a different program, but it still looked like shit. The problem with this was that at some point I had switched from airbrush to paintbrush, and didn't realize for a while that I never switched back to airbrush, so it doesn't look as good as intended. But yes, contrast would help too, but I'm done with this sucker.
drawn in 59 min
Purple, blue and yellow, all good.