Good painting! Better than I could do though, only thing I can really say is make the shadows darker. This will give it depth, sorry to critique ^^' I don't know much about humanoid drawings so thats all I can really say.
Thanks. Look at the artists you like and make a mental note on their technique; what have they done that makes their work a success? A brush stroke? texture? pallet? Sorry if that's kind of a cop-out answer like "practice makes perfect", but that really is what I do.