Develop good rehearsal habits:
Warming up before rehearsals will help you avoid straining your voice. During a long rehearsal, be sure to take breaks and drink plenty of water.
Always use a microphone when singing with an amplified band. Position yourself so that you can hear your voice from an amp or monitor. Singers who cannot hear themselves tend to compensate by over-singing. This is a sure way to wear out your voice.
It is important to prevent problems by knowing yourself, your voice, your limits, and how to take care of yourself. Many singers complain of being sick with colds and various illnesses all year long. However, if they were to examine their daily voice use, practice habits, and vocal hygiene, they would probably find that they are slighting or ignoring some basic elements for maintaining good health. If you follow these basic precepts, you will have a better chance of fighting colds and getting through the season. Use common sense. Rest your voice, eat right, and get enough sleep.
Happy Singing!!