Why wouldn't you want to quit? Singing is basically airflow coming out smoothly, Any time you smoke or inhale harmful poisons such as those found in cigarettes it damages your lungs. There may be tips to help on a short period of time but the more you smoke the worse it gets due to air moving out of your lungs unevenly. Listen to some voices of those that have smoked for year, they are very different from those that don't and also usually accompany coughing. If you are looking for a long term carreer in singing, the only answer is the one you don't want. By all means, if you can find 1 good thing about smoking that I can't argue with I will take some time to help you find a solution. Go ahead, try :]