watch out the face, you used very, very harsh shadows here, and you didnt really made a new one, you just drawed over the old face, taking the same structure along. the face could use way more variations, more colors and a little bit more care.
the armor is a mix of green, lightning and shading, but you should use more than one color, its nearly impossible something in reality have only one base color, it might have a general color. you could, for darkening, use a little bit of blue, for example, it would be a good step.
tone down the amount of BLACK, thick lines, they're highly unrealistic, saying this is only a skin isnt a good reason, good skinners know you gotta make it as real as possible, not set yourself boundaries. the helm is a good example of excesive black lines. since that on the portrait, the helmet have a very important role, you should've taken a bigger care to it.
but anyway, it is an average skin on the wc3search scale. try, no wait, you must develop your shading lightning a bit more, learn to do credible faces, and use more than one color ( darkening/ lightning on the same hue doesnt count ) on your works, its a challenge.
you might want to use a special burn&dodge setting, but i still suggest choosing your color from the color palette