[Nomadik]

I'm a complete loser when it comes to the world of shading and highlighting. I try, but truthfully, I suck... =) My art background relating shading basically comes from Mark Kistler's Imagination Station.. hehehee =) I know stupid simple stuff, like pick out where the hell the sun/lighting is, and then shading opposing to that, and if there is intense light on a specific area highlight that, but anything else I'm pretty clueless.. I don't think my shading is very good at all... If you want to thumb through my artwork, I do have a website at: http://nomadik.virtualave.net/ Any help would be useful. Perhaps someone has a tutorial?
Thank you,
Jesse