1. If you don't drink you will never get a hangover.
2. Don't drink to excess. This way hangovers will be rare.
3. Don't mix a lot of different alcoholic drinks. (beer, then liquor, then wine)
4. Alcohol is a diuretic so it causes dehydration. Drink 1 or 2 glasses of water before going to sleep.
5. Although aspirin, acetaminophen, and ibuprofen are widely thought of as a hangover cure, you should never mix them with alcohol. Acetaminophen metabolizes in the liver and can cause extremely dangerous side effects. Aspirin and ibuprofen are stomach irritants and don't mix well with alcohol.
6. Get plenty of rest. This will help your body recooperate.
7. Try to eat something to help replace the nutrients you've lost. Eat foods that are easy on the digestive system. No greasy foods!
8. Having another cocktail the morning after (hair of the dog that bit you) may ease the pain, but most likely it will just put off the inevitable hangover.