Water intake

Just pay attention to the color of your urine. If it's a pale yellow, you're fine. A darker color means you need to drink more.
It doesn't just have to be water either, it can just as well be fruit juice, milk,... or even foods with a high water content (fruit,...).

My coach always says it's not a perfect system.. but take your weight, cut it in half and that's roughly the amount of water in fluid ounces you'd want to drink daily. Correct me if I'm wrong please!