wooba, there’s a difference between what will get you more drunk and what will give you a bigger hangover. As far as hangovers go, J String has it right: it’s all in the congeners; the more there are, the more severe the headache.
As far as getting drunk goes, there are several factors that can speed up how drunk you get: drinking on an empty stomach; eating starchy foods while drinking (this gets the ol’ pyloric valve in action, whereas eating greasy food slows it down…so chow down on chips & Buffalo wings); drinking carbonated beverages (eg, those Rum & Cokes will get you drunk quicker than Rum & fruit juice); and drinking while sitting down (stay standing while drinking to slow down intoxication.
But you’re right that water is a factor too. My recommendation for avoiding, or at least mitigating, a hangover: set an alarm for 2 hours before you actually want to get up, and when it goes off drink 3 big glasses of water and take two aspirin (Tylenol not recommended, which when regularly taken with alcohol in your system can cause liver problems). When you finally wake up 2 hours later, you’ll feel a world better than you would otherwise.