As someone who LANs once a month and usually goes from 9am-8am the following morning, crash for two hours then 10-5pm, I can vouch that the whole "you'll damage yourself for days" thing is wrong. I usually hit the hay at about 10pm on the Sunday night, then get up at 8am and do a full day's work feeling no worse than if I'd stayed up until midnight without the all nighter. It won't make you any healthier, and it's certainly not going to kill you.
As for tips, fruit juice is a good one. In my experience, Caffeine basically keeps your fatigue level stable, as opposed to actually lifting you. That is, it won't make you feel any more awake, all it will do is stop you getting more tired. That said, as it wears off, you will start to drop more quickly than normal. They work, but how hard you push them is your choice, but keep in mind that you'll probably hit your B12 limit before you hit the caffeine limit, and neither of them are nice on the way back down. Fruit juice won't give you that same high, but something like orange juice is acidic enough to keep you awake without too much of a problem. If you can, get up and move about periodically. Go outside for a few minutes, walk up and down a staircase, get the blood flowing again. Getting oxygen into your system will keep you going as well.
When you wake up in the morning, fruit fruit fruit. You'll get something similar to a hangover if you top out on caffeine, fruit juice/actual fruit will get that bottom-of-a-bird-cage feeling out of your mouth pretty quickly. It also helps if your playing area is crash-friendly, a sofa or something rather than a high chair above a solid floor is always recommended.
Lastly, there's a breathing exercise that you can do, it won't clear fatigue entirely, but it tends to give me an extra hour or two:
Stand up, take a few deep breaths. Close your eyes and visualise an outline of your body, as though you're facing yourself. Fill the outline with a colour (I use blue, for example) and imagine that you're pushing a board down the outline, pushing the colour downwards. As you do it, imagine the fatigue leaving the parts of the body that aren't filled with colour, and draining line water from the tips of your fingers and your feet. Keep pushing down until you get past your fingers, then down your legs, and finally to your feet, all the while breathing deeply. When you're done, open your eyes and walk around for a few seconds. You won't feel perfect, but you'll feel better than you did previously.
Hope this helped!