Udisha
Whispering
This might not be as obvious, but when you whisper, the vocal chords come together tightly causing friction. Whispering does not allow the chords to vibrate naturally, and your voice ends up drying faster. If you are worried about your voice before a singing performance, speaking in a normal, relaxed tone is safe enough.
Clearing your throat aggressively
Even if you think that your throat is congested, do not clear or throat; it does more harm than good. Aggressive throat clearing leads to friction and inflammation which can affect your voice. If you feel the need to clear your throat, drink a sip of water and gently swallow.
Munching on dry snacks
Just like eating heavy and spicy food before a performance is not the best idea, avoid eating dry foods such as cold sandwiches, nuts or other crunchy snacks that can leave behind tiny particles in the pharynx which can cause sudden coughing fits.
Over-rehearsing
It is widely advised to not rehearse and over-strain the vocal chords right before you get on the stage for your live performance. A well-rested voice is a singer's gift. However, stick to simple, gentle warm-ups for 10-15 minutes and have faith in yourself.