The outlines around the face and snakes really need to be made a little bit more visible; if you're using layers, you should have the linework locked on the topmost layer, and colour on seperate layers underneath that. Check out www.polykarbon.com for some really helpful tutorials.
I can see where you're heading with this, but it's just got a few minor shortfalls - the pixellisation (or 'jaggies') around the linework, for example. You really need to work at a much higher resolution than you'll eventually be publishing at - computers can downsize images with very little bother, but try and expand artwork (unless you're working with vectors) and you'll run into problems with pixellisation.
Sort out these small problems, and you'll have a very promising image.