Window Tinting Questions

I'm not sure if this belongs here or not but anyway I'm looking to tint my windows but i've never done this before local places want 120-150 to do it so i thought this would be a good time to learn and save a couple bucks where is a good place to buy the film and what advice could you give also do you know of any good websites that walk you through its going to be done on a 92 b2200 i'm probably just go with a dark black what % tint is that also places like autozone and walmart sell tint film is it worth it or is it crap just need some advice thanks in advance