Hydration in the build up to a heavy session is key, make sure to drink plenty of water for a t least 2 days before.
Once the hangover is there though time is the only healer, everything else is just a distraction technique, well apart from drinking again which just delays the inevitable.
As an aside anything that involves effort or particularly driving somewhere for a walk means you just have a very mild hangover. A proper hangover is being too hot and too cold at the same time combined with a total sense of unease, where even the thought of washing up feels like being asked to captain a mission to Mars.