Speak as little as possible the day of your stage performance. Some go as far as not speaking at all, but this is not possible for everyone. Talking can actually harm your vocal chords more than singing, so just keep it to a minimum. Also, speak to those around with moderate volume. Shouting and whispering can be harmful to your vocal chords.
Take a hot shower. The steam will help warm up your voice before a performance by adding extra moisture. You can also place a warm air humidifier in your room prior to the performance.
Warm up with moderate scales 2 to 3 hours before your stage performance. Avoid singing too high or loud and too low or soft. Keep your warm ups in the middle range.
Drink lots of water. A dry throat and mouth can be detrimental to your voice before a stage performance. As a rule, drink at least 8 to 10 glasses of water per day.
Vocalize the scale, steadily, while saying the word knoll. Use a soft voice for this exercise. This vocalization should use the notes close to your lowest note and close to your highest note. Be careful not to strain your voice to the lowest low or the highest high during these warm ups.