Learning Texturing
 

I know how to model quite well its just texturing I know nothing about.

I've tried learning photoshop but my textures just look really bad because I dont know what I'm doing.

I've tried looking for websites but none of them have helped

here's an example of me trying to paint a metal texture for an ammo clip :(

can anyone recomend any decent websites,books or will it be a case of trying to find a course that teaches texturing?