What products and growing tactics/methods/etc.. do you swear by?

I'm in my second grow, and still getting the feel for what products I like vs. don't like. That's what gave me the idea for this thread. I extremely apologize if this has been done before, but I searched and didn't find anything.

I figured asking some of you guys might help me side-step some of the pitfalls I may run into. (learn from other peoples mistakes!) So?