Just finished up 7 weekends of four half hour shows plus a few mini-sets a day at an outdoors dusty and HOT Renaissance Festival.

With the exception of the weeks bracketing the nasty cold that I got, I found that as long as I a)didn't push my voice too hard, b)drank SOME water/gatorade, c) didn't yell or scream everything came out well.

If you don't know how to already, learn to project. Even if you don't learn to fully utilize it in singing, an audience is normally fairly attentive to a song and you can get away with slightly lower volume. But having that projection can be a lifesaver in many ways... you can keep attention between numbers, make sure the audience knows what's coming next, and also shoot down any heckler in the audience because YOU are louder AND aimed at the crowd...

M