I usually wear a hydration backpack. I have a Camelbak Blowfish. It holds 2L water and has a small and a large zippered pockets.
What makes riding so interesting is not just figuring out the chemistry of your metabolism and how it interacts with your energy levels, the muscle fatigue from a previous ride, and then external factors like wind, humidity, and barometric pressure.
As you learn to pay attention to your body, you'll adjust your ride goals appropriately.