[Tangster]

Go to your local library and take out some books on:
-anatomy
-composition+depth(photography books are best for these)
-General drawing techniques(the ones that normally say "you can draw anything")

Also practice drawing cylinders, spheres, and cubes in different lights to hone your shading and highlight techniques. Start with a paper and pencil and avoid using a rubber.

EDIT-if it helps you can draw something, PM it to me and I'll try and point out where it's wrong and help you correct it.