Eat a protein rich soup - Mexican people swear by Menudo, a brothy soup beside tripe in it which sounds foul. I like pho, or posole, or old-world chicken noodle. They are salty to help you rehydrate and they hold nutrients and the warm soup feels right on your head and like a melt bath.(slowly, if you can stomach it), have a spoonful of honey- someone told me it somehow bonds near the alcohol (not sure how, but it works). Have plenty of water and a bit of caffeine (shrinks your head a little). Rest and babe-in-arms yourself and try the honey before you go to bed subsequent time with a HUGE glass of sea.
Yes - drink lots of water. The hangover is from being dried up.
To prevent a hangover, when you are out drinking, drink a glass of water every other drink (e.g. hold an alcoholic drink, then water, after alcohol, then water, etc)
Plain, cool but not cold, water. Sports drinks own lots of sugar and dyes in them that can actually further dehydrate you. Drinking a cup of water between all your alcoholic drinks will assistance prevent a hangover, which is better than curing one.
Drink a banana milkshake, works miracles.