Don’t reach for a cup of Joe just yet. Coffee, like alcohol, is also a diuretic, and could actually worsen your headache. However, if coffee is part of your regular habit, drinking a cup may be negligible and might give you a small boost.
Exercise requires hydration and nutrition. Drinking dehydrates you and the metabolic process that's required to break it down leaves you behind on your nutrition. Opt for rest.
While over-the-counter painkillers can ease hangover symptoms, be cautious on which ones you choose. Ibuprofen is strenuous on your already overworked liver and can cause further damage.
A large, fatty meal is better at preventing a hangover than curing it. Fat can pretreat the stomach by insulating it before you drink, but afterwards will simply irritate it.
Hair of the dog
Yeah, it may take the edge off, but it’s making you more dehydrated and will lead to worse hangover symptoms later in the day.