What should I do if my teen has started to smoke cigarettes?

Teen smoking. Teen smoking is the gateway to other drugs/alcohol. Talk with her to discuss the pros and cons of smoking cigarette, and how to quit. Changing behavior is not easy, but is certainly doable.
Smoking tobacco. Education is of prime importance. Discussing the negative effects of smoking on the lungs, heart, circulation, etc and the inherent fact of addiction and its difficult cure should be attained. As a role model, any close family member should not be smokers as well. Association with non-smoking friends should be stressed.