According to my sister-in-law, a trained singer with a gorgeous voice, luke-warm water.

According to a voice doctor interviewed in People Magazine, avoid caffeine, chocolate and alcohol, all of which dry the throat.

General knowledge says that if your throat is phlegmy, drink fruit juice, but don't overdo. Clear your throat, but don't strip it.

According to my high school glee club director, do not drink carbonated beverages before singing.