clipped from: www.drweil.com   

1. Moderation is the best way to avoid hangovers - make sure to pace yourself.
2. Eat food if you have more than a drink or two.
3. Avoid dehydration (and cut down on alcohol intake) by drinking as much water as possible while you're drinking alcohol.
4. Take a B-complex vitamin supplement plus extra thiamine (100 mg) to counter the B-vitamin depletion caused by alcohol.
5. Choose beverages that are "cleaner." Some distilled beverages are rich in substances called congeners - toxic impurities that can greatly add to your woes. Bourbon, rum, and cognac are particularly dirty, while vodka, which is just pure alcohol and water, is the cleanest.