How to get the Right Textures.

I'm not the best modeller in the world but I can get basicly what I want. but It ends up looking pathetic bacause of my inablility to get the textures right. Are there any techniques that help in making a texture suite the image or does it just take practice.

sketches on paper help :)
once you get a good picture then go ahead and do it in 3d...

Thanks I'll try that when I get a chance.