Ok, seeing as how I deal with this on an almost nightly basis, here is my advice.
Drink shittons of water BEFORE you go out and start drinking. Drink as much water/alcohol as you like while out having a grand old time. HOWEVER, once you vomit, you should stop drinking ANYTHING. The reason for this is because you have now offically poisoned your body, and vomiting up whatever is in your stomach is a common occurance. Drinking anything after vomiting will probably just cause you to vomit again, and at this point in the night, you probably just want to sleep...so we don't want to choke on our own vomit, now do we? This is why people say you shouldn't drink water after a heavy night of drinking...not because it is harmful, as small amounts of it generally aren't. But it is simply do the fact that choking on vomit from being too drunk actually DOES KILL PEOPLE. Just something to think about.