Art Shading Practice

Here's a picture I worked on for a couple minutes to try and get a hang of shading (which most of you, who have seen my art at least, would notice was completely and entirely lacking)... unfortunately I believe this is a pretty poor attempt and no matter how many tutorials or real-life examples I look at I just really can't seem to get the hang of this... I don't know... maybe some day.

The character is Lee Marshall, a mutant I made for an Marvel RPG campaign I'm playing with my girlfriend and a few of her friends. Currently just a Telepath (with telekinesis, as well), but eh... evolutions will occur. The picture isn't completely finished yet either, will be adding my second character in later. And yes, the paper I was drawing on is kinda weird, but I actually liked it a lot more than the typical white printer paper I use.

All comments and, especially, criticism would be greatly appreciated

 

The linework is good and clean but as you said, the shading needs work. Right now, it's a bit tough to tell where the light is coming from. As a start though, I can see potential for a good shading in the pic. Some additional shadows and maybe the use of some gradients would really bring it out.

 

I in fact like the paper you used. I don't really like white paper all that much but people have to use it for manga and all that. The hair of the guy looks really great to me since I think that is the hardest thing about characters but I don't know very much about it. I can't tell where the light comes from. Is it over him, to the sides...something If you add background and more shadows to that picture, I think it would look really good.