Drink lots of water the night of and take tylenol before you go to bed. Always worked like a charm for me. Ive also noticed that darker liquors, beer and wine tend to produce hangovers vs lighter or clear stuff.
Do not *ever* take Tylenol or anything with acetaminophen after drinking alcohol! It can cause liver failure! Like the previous posters said keep yourself hydrated and if you have a headache take ibuprofen or naproxen.
I personally am a fan of taking alka selzer before bedtime. I usually take it at least an hour before bedtime, and in the morning, guess what?......no hangover. When I wake up I usually have a good breakfast followed by a day of rehydration.
Your body as well as water also needs salts and minerals that have been lost during drinking and visiting the toilet… A good tablet or two like a multivitamin and/or multimineral is a good thing to complement the water. Alternatively take some mineral added salt and get that down with some water. Keep drinking water or gatorade throughout the day. Cheers!