How you can improve on that one? Mmh ... I think the green skin looks too dead. I think you went for your highlights with adding a little white to it. Next time make it more alive. Not only going from dark to bright with black and white. Add for example some yellow or orange to your green basic tone. Highlight it with a mix from white and yellow /or/and orange. You will have a much more satisfying result in the look of the green skin and in the way you blend. It makes it easier.
But he is not painted badly, Denniz ;)
Gold and added to favs list.gr8 job dennis.