Drink water, don't drink coffee and other caffeinated drinks, and sleep early. I got Pfizer, first one felt like a mild cold, second made me borderline braindead for a week and I'm going to get the booster soon -- something I'm NOT looking forward to. So it's 2+1=3, not 8973 like Reddit tier boomer memes imply. Had really good sleep though.
Anecdote for what it's worth, I have two double-vaxxed friends with Omicron (caught from a club) and they are experiencing zero symptoms. Another with it had one jab and he's stuck in bed miserable as all hell. All three are healthier than I am at the very least (because they don't broom Kiwifarms I guess).
Oh, and it seems like some are surprised that most who get Omicron among a population of 90% double-vaxxed are double-vaxxed, damn. Most thieves in Japan are Japanese, I'm surprised.