That's a nice illustration! I think the main feedback I would have is about the lighting. The main light in the cave is the little baby phoenix (which is really cute!) So things close to him should be really bright, but right now you have some inconsistency as the face is lit very brightly compared to the arm and hand that are much closer the the phoenix.
Also and this is more of a preference I guess, I'd make the edgelight (for example the lighter edge on the cape on his left shoulder) more towards a blueish color to reflect the color of the sky as, technically, that's the sky who would cause that light. I would also add some on the hair too!
I did a very quick and rough paintover, but hopefully it will help you make sense of what I said
I hope this helps!