One word of caution about supplements:
If you compete in a league that is subject to drug testing, it is up to you to verify that a product is cleared for use. The guy in GNC (a popular US supplement store) will probably say anything to get you to buy the latest-greatest, expensive thing in the store. "Sure, bro. It's legal to take it. I got customers that play _________ that take this all the time."
I personally stick to the basics: Creatine Monohydrate, Whey Protein (with as few additives as possible)...and I don't even use those year-round. Maybe only a few months. It simply gets old and tiring to me.
There was a masters racer back in 2010 or 2011 that took a popular supplement powder/drink and won a national championship (points or scratch race) and was randomly tested and was found to have something on the WADA ban list in his system. The story is that the guy was mortified and immediately said, "Yeah, I take [product name] all the time! I had no idea it had [banned substance] in it." and was apologetic about the whole thing. I don't know the guy, but many truly believed that it was an honest mistake.
Keep in mind that some banned substance may be listed with a different name on the product label.
Here is the WADA Prohibited Subtance List:
http://www.wada-ama.org/Documents/Wo...st-2013-EN.pdf
There used to be a searchable online version. I can't find it. I also think there is a WADA iPhone app as well.