[tigeba]

If you want to eat a banana before you singing go for it. Things you eat or drink don't touch your vocal folds, so they aren't going to coat or otherwise mess with them.

My recommendations are drink plenty of water, avoid alcohol, and practice.

[failrate]

Another thing to avoid is extensive speaking. Normal speaking is surprisingly detrimental to ones singing voice.

Other folk remedies for voice include flat, room temperature Coca-Cola. I don't think anyone has demonstrated efficacy of any of these techniques, but another big factor in effective singing is mental state. If a placebo ritual helps get you in the correct frame of mind to sing, then it might just be worth doing. The destructive alternative is to get intoxicated before a performance.

[tigeba]

Agreed on the talking. Especially if you are in a club before a show. Talking over the noise is taxing.

[peglasaurus]

Talking over background noise rapidly becomes quiet shouting especially in a club.

[lloeki]

My wife is a singer. That’s her top recommendations above, plus good sleep. Her voice derails with a bad night.