From: Chaka Wolf
Some things I've learned:
1. You can dance with your upper body only. It is not as much fun, but you don't get tired as quickly.
2. You can dance to every other beat instead of every beat.
3. BEG the firsuit wrangler to put a fan in the dance area! Usually fans are scarce, but I've seen it done, and the difference is amazing.
4. If you feel tired or dizzy, don't stay until the song is over. It takes a while to get to the headless area, and you need to get started!
5. It's usually dark in the dance. Go in street clothes first and locate exits and possible trip hazards.
6. Remember, dances usually last for hours. You can take a long break and still get plenty of dancing done. You can even change, dance in street clothes, and change back. You don't have to kill yourself in the first fifteen minutes! There is plenty of time to kill yourself slowly over two or three hours.
7. If the DJ has a special time slot for slower music, take advantage of it!
8. Be aware of others on the dance floor. If it is really dark, find yourself an open area where you won't bump into them. Having said that, be prepared to bump into other dancers anyway.
9. Have fun!
For me, a heavy factor in what determines my time between breaks is the breathability with the costume head on. If I can get a good airflow in the costume head (no fan even needed), I can last a long time in costume between breaks, even on a warm day in a suit padded head-to-toe with foam. (I'm also pretty heat-tolerant, though.) I've done more meet-and-greets than heavily-active performances – but, should a situation require me to be heavily-active, I'll be able to keep it up better with a better amount of ventilation.
Otherwise, if there's not much of a way for air to flow in and out, I find myself having to take breaks more frequently – or at least, if I'll need to be out there for a long period of time between breaks, I pace myself to make sure I can still give the best overall performance that I can give.
A good diet and steady liquid consumption also helps out quite a bit in how long I last out in costume – not only before the performance, but even during breaks and after the performance too. While sweating, you not only lose out on water, but also sodium, potassium, and other nutrients, so it's important to keep a steady amount. There's actually a nice page off of MascotNet that highlights all this: