Your best piece so far, although you might take it a bit further.
Looks like 8 colors (not counting transp), why does it have 17?
Needs some anti-aliasing; also there's lots of banding. Check for those here.
Thick black outline can be a stylistic choice for some pieces, but it doesn't really fit this one (although this is more a matter of opinion than technique).
Did you use a reference picture (good) or draw from life (better)?
i like your style dude :D