The background isn't really great, the cracks kinda remove its depth.
The colors don't seem to fit too well: green for the background,yellow for his hand, blue for his staff, orange and red for the right side...is this a rainbow? It should've been yellow left and blue right, so you could've played alot more with those two colors.
The little blurred dirt-like effect blue effect you added on the staff flattens it further.
Again, to improve, put less but better layers in your work, this render's colors demand something to be done with them! Like...hot in the left and cold in the right? Seems interesting to me!
So yeah, focus on a concept when creating your works, rather than trying to do what you feel best doing.