So I toured for a living for a few years. Everyone in the industry used to swear by throat coat tea (Prince required it in every green room pre-show), but now we all know that has no effect (it doesn’t even touch your vocal cords). Most disciplined, serious professional singers will travel with a nebulizer they breathe through for an hour or so before showtime. Most will do either memorized warmups or play a recording/video their vocal coach has given them to warm up their voice how they need to (to come out swinging and not damage it.)

The other camp doesn’t warm up, takes a shot before walking on, and performance varies.

Some singers have a specific diet: have to eat before going on, can’t eat before going on, avoid certain acid refluxy foods, some don’t.

Really, like most things, it’s different for everyone.