your hangover is hopefully gone by now but loads of water helps.
hangovers are apparently caused (or exacerbated) by dehydration so drink plenty the morning after. or alternate between pints of water and pints of beer/cider/vodka on the night. probably stay away from coffee or other stimulants, itll be a quick fix but come back to bite you later on in my experience.
also eat plenty. i'm almost always ravenous post-drink so that's rarely a problem for me, but if you feel sick in the morning maybe grab a kebab on the walk home?