So much good info here from knowledgeable people. I am not an entertainer, but I do sing at convalescent homes, and some are really nonresponsive audiences, which means no interaction, just me singing one song after another for 45 minutes. I've found it helps to start with easy stuff to limber up (and loosen up), and keep those songs with a range that is a stretch until I'm feel ready to reach for it. I go for diction over volume...it's a great aid to projection without strain.

My own experience is that anything with sugar (or any kind of sweetening), including throat lozenges, syrups, etc. will clog my pipes, and I too, sadly, find alcohol to be a disabler. So it's boring but effective water in small sips.

Good luck...bet you knock 'em dead. How long do you have between sets?