Hey hey hey! My man Teej decided to join the party! I'm glad your posting here.
There are a few pieces that get posted here at pixelopolis that everybody just LOVES to edit. Yours, my friend, is one of them. You have a very solid base here with a good sense of lighting. I also like the hue shift on the skin towards blue. Listen very closely to Ptoing about the colours - He is the grand master god of colours and his advice will be very useful. Also make sure you clean up those lines to make them all nice and smooth. It will increase the quality tremendousely