By symptom:

General fatigue:

Take a bath. The hot water will soothe and relax muscles tense from overexertion on the previous night and a more than likely bad sleeping position caused by having collapsed into bed any old how. For a stronger invigorating effect try having your bath in a cold room - leave the bathroom window open or something.
There is no subsitute for good old headache pills and lots and lots of water. However, for burning eyes and throbbing forehead relief, you might want to try one of those refrigeratable beauty eye-masks (available from Boots or the Body Shop to name but two). Keep it in the fridge and put it on until the pills and water start kicking in.
Dry mouth:
Again, water is good. Also brushing teeth and using mouthwash - try gargling with it for an extra fresh effect that will make you thirsty as a special bonus.
Residual nausea:
Use some kind of bath oil or essence fragranced with a fresh, zesty smell: lemon, eucalyptus, mint etc.
Lack of energy:
Rehydrate with something sweet - not Coke because it's acid and your stomach doesn't need that, and not coffee or other hot drinks because you'll probably not drink enough of them. But orange squash or Ribena will give you a nice sugar rush to keep you going until you're finally fully awake and feeling OK. Fruit juice is also great.
Sick, lifeless feeling:
Pop a couple of all purpouse vitamin & mineral pills - you've sweated, pissed and probably puked a lot of your body's daily requirement, and it wants it back. You'll also need salt which can be obtained from some peanuts or crisps.

So there you are. Lie back, enjoy, drink sweet drinks and munch junkfood for breakfast, and you're guaranteed to feel better in half an hour - handy for when you've got a day of work in front of you.