The best study method is to put effort in over the quarter/semester, and then get a good nights sleep the night before the exam. (Or, to work on the paper/project over time so you're not cramming--this is personal experience talking, unfortunately!)
That said, caffeine does affect people differently! I, for example, wind up simultaneously exhausted and jittery if I consume caffeine in lieu of sleep. So, not only am I unable to function smoothly, I can't hold still! I have a close friend who discovered that caffeine actually puts him to sleep, which doesn't help much! I can't lie--I'm a little jealous of those who can have caffeine and have it boost their mental productivity. (I do have coffee and carbs before the gym, it helps me then!)
I would argue that Redbull/Monster/etc are worse than coffee (both because of caffeine content and sugar content) as far as health goes.
Someone else answered that water is great for studying--which is true! If you are dehydrated, like most of us are especially if we're chugging coffee after coffee, your brain and body don't work so well.
Bottom line: caffeine affects people differently, you'll have to explore how it affects you on your own. Studying over time and getting proper sleep, as well as staying hydrated, is the best 'study tool'.