okay, but it's so simple. You could have taken this forward a few more steps. The dark green doesn't fit so well, but it's good you're trying to hue shift. I think take it a little more towards gray and then take the middle gray towards green a tad, and maybe take the lightest shade toward yellow. I'm not trying to say "this is how you should color it" but really you should play around with the colors much, see what works and what doesn't, experiment. Maybe add some shades to give the face more depth, and expanding upon it, the overall structure is nice just could go further.