How To Cure A Hangover

We've all been there. You're out having a killer time partying. The next morning seems far away and you keep making excuses to yourself about why it's ok to have "just one more drink." Before you know it, the clock strikes 2 am, the bar is closing, and you realize that you've got to be at work in less than seven hours. You're screwed!
Hangovers are caused primarily by dehydration and impurities in what you were drinking. Your body has to filter everything you drank the previous night including the alcohol out of your system. The main symptoms that you're feeling, nausea, headache, dizziness, are caused by dehydration.
Once you've got a hangover you're pretty much stuck with it until it passes. Try to hydrate, eat something healthy, and wait for it to go away. If you're particularly adventurous and the hangover isn't truly horrendous, I've found that some light cardiovascular exercise can help. It feels like you're sweating the alcohol and impurities out of your body. Only attempt this if you're relatively healthy, free from heart conditions, etc...
The very best way to defeat a hangover is to stop one from occurring in the first place. The number one rule is to NEVER GOTO BED WASTED! I know it's easier said than done, but try to stay up for an hour or two past your last drink. Eat something healthy and most importantly drink lots of water.
Hydration is the key to avoiding a bad hangover. It can make the difference between calling in sick the next day and showing up with a light headache. I'll drink several cups of water before bed and keep a jug of water on my nightstand. Whenever I wake up throughout the night I'll take a swig. Drinking water really is the only way to lessen the effects of an impending hangover.
I've tried just about every hangover cure in the book including vitamins C & B, Bloody Mary's, various foods, etc. The only thing that's ever worked for me is to eat before bed and drink lots of water. The longer you can stay awake after your last drink, the less your hangover will hurt the next morning. Granted, that's not much of a solution if you've got to be up in six hours...
Although some people will recommend a Bloody Mary, drinking the next morning to avoid a hangover is not the answer. It may make you feel better but it's only temporary. You'll have to pay eventually and why not just get it over with? Drinking first thing in the morning probably isn't a very healthy choice as it can become habit forming which can lead down a road that no one wants to follow.
The key items to remember about hangovers are hydration, getting some food in your stomach, and sobering up a bit after your last drink. The very best way to avoid a hangover is to simply limit yourself to no more than two drinks.