I had twenty or so minutes on hand, so if you don't mind, here's a quick paintover I did.
Here's a breakdown of what I did:
I used the liquify filter to push around his face. I moved his ear down, and I extended his hair higher and his forehead lower. The hair usually covers more of the skull that what you had. I made the jawbone and chin smaller and less prominent, as in their present state they seemed too large for me to think of them as elven features. I think that's all I pushed around.
Then I shaded his face differently. I used more contrast for one, to make the picture have some more drama about it. I also improved some of the layout of the shadows and light to better suggest his face. Namely, I put more shadows around his eyes and the bones there around to make them look sunken and to add to his malevolent look. I changed him mouth a bit, and heavily shaded his neck area. I think it'd be dificult to explain everything of what I did on his face, as it was more intuitive than deliberated. It will come with obervation and study.
Then I extended his hair down and changed that strand in front of his ear. His hair looks like it is very long, or perhaps it flows into a robe he's wearing. I left that up to the imagination of the viewer. I also made the highlights in his hair smaller and more specular, as they usually appear in hair.
After that came the background. Didn't put much thought into it really. I know it is the opposite of the lighting scheme on his face, but it doesn't really matter much, as there is more contrast this way.
That's about it. I tried to make him look more evil in general.
I really like what you had there, both faces; don't get me wrong. I liked it enough to fool around with it, in fact, as I found the pictures inspiring. Or the theme. I like the sketchiness of the pictures and that I can see the brushstrokes. There are some technical and anatomical issues you have, but they are nothing serious and can be remedied quite simply. I like the female's expression, and the smooth shading on her skin is great.
There's not much more for me to say as I will probably start to become more redundant than I already am. Fine work you have, even if they are sketches, but I can see the potential in them. Keep at it. Your brushwork and shading is great!
