As most of you well know, there are a few universal truths regarding what to do or not do prior to a vocal performance. First of all, to a large extent, you are what you eat! Dairy products, e.g. milk, cheese, yogurt and ice cream as well as chocolate and bread will coat the vocal folds, causing them to vibrate more slowly and produce a fuzzy and unclear sound. Caffeine, including cola and Mountain Dew, will dry the vocal folds and make them sore when they vibrate. If you consume a lot of caffeine, you will tend to lose your voice more often.
The best foods to eat before singing are non-spicy chicken or turkey, clear soup, and fruit such as apples, grapes, oranges and lime or lemon wedges. Above all, DRINK A LOT OF WATER! And if you value your life, NO GARLIC or ONIONS! Needless to say, alcohol is high on the list of no-nos for a variety of reasons.
It's especially important any time we're on the risers to skip perfume, after shave and scented hairspray. DO schedule your yearly bath prior to performance time, and add some unscented deodorant for good measure. You may want to apply a little Vaseline or lip balm to your lips to keep them from sticking to your teeth when you sing.