Basically a hangover is dehydration and an upset in the electrolytes. So a large glass of water with a bit of salt and an EmergenC packet is the best and easiest cure that I know of. :)
After a weekend of heavy drinking it would be wise to drink some carrot juice and/or take a few Livatone Plus pills to help the liver keep breaking down the alcohol. B vitamins are good too. :)
Because alcohols are a kind of sugar, sometimes the hangover is hypoglycemia. In that case, eat complex carbs (whole grains) and a protein shake.