Tweetthis is a very broad question buddy.
But to answer your question, it really depends on number one: your goals, number two, what kind of gear you are doing.
I take suppliments year round on and off AS. I always include in my suppliments, Glutamine and amino's on AS, and off, I like Creatine, ZMA, 1 AD (when I am desperate), Xenedrine, etc.