mainly I've noticed I play better when my brain activity is low! like after having a meal or with the air conditioner on, both of these activities result in less brain activity but somehow I play better
Warming up for a match - what does it for you?

Everyone is different, but personally if I have an important match (or tournament) coming up then I avoid much chess beforehand. I might "warm up" with a few (key word being "few") puzzles or tactics hours before the event, but I certainly try to avoid any chess games that day (to avoid getting burnt out before the event).
Earlier in the day, I might get something to eat, play a game or something (just not chess), or even take a nap. The point is to not do something too mentally straining, so you will be fresh when your brain really needs to think well

Back in my OTB tournament days, I used to get ready for a tournament game by playing over some well-played game that I had won previously.
The point was to give myself a confidence boost and go into the next game with a positive attitude.

That's also a very interesting point. I wish I had waited a little before posting my blog. Maybe I'll just link to this forum as well.
BTW the blog can be found here.
I'm one of those players who have to warm up a little before I can play anything worth mentioning. I usually need just a simple position, most of the time it's an adjourned game I have set up on one of my boards, and I feel something click - the moves start turning like the gears in the clock.
Sometimes I avoid tactics as a warm up exercise because these can get quite frustrating at times. Try playing a game after a tactic made you red in the face. Sometimes a little blindfold chess does the trick but I feel it doesn't quite prepare my eyes for the lights, the screen, and the board.
What does it for you - what gets you ready for a good game?