Do the best to avoid smoke-filled rooms and don't hang around smoky areas on your breaks.
Avoid alcohol and caffeine while performing. As mentioned above, they can dry your body and vocal mechanism. Alcohol can also alter your perception of how loud you are singing, impair your ability to sing in tune, and lead to unnecessary strain. Drinks containing alcohol and caffeine can also lead to reflux laryngitis.
Throat clearing is hard to avoid when you have a stubborn spot of thick mucous rattling around and you're trying to sing. Clearing your throat will remove the bothersome mucous but can also irritate the leading edges of the vocal cords. When practicing, try to sing the mucous off. If you must clear your throat, do it gently and avoid habitual throat clearing.
Performing environments such as theaters, clubs, and bars are often dusty, smoky, and noisy-all things to be avoided by singers. While often this is not possible, singers can take some measures to help prevent vocal burnout.
(Note: These guidelines are not intended to be a substitute for professional medical care. Consult your physician if you develop health problems).