stoned said:

How to quit smoking ?
It depends on why you smoke.
If you're quitting through an organized program and planning to quit on a certain date, switching brand to brand ahead of time, especially if you're using lower tar and nicotene ratings helps a little, at least psychologically. Hell, if you switch to a disgusting enough brand, the actual quitting might be a relief.
The physical part only lasts a few days. I just sleep a lot the first day. It gets easier every day after that. The physical part is worse for a lot of people. Nicotene patches or nicotine gum generally help with the physical addiction.
The psychological part is hardest. You have to find a substitute for all the little things cigarettes did for you. If you smoke a cigarette because you have to think about a problem away from your computer or your desk, you have to find some other excuse and/or activity (funny how a person feels they should be working instead of thinking unless they can find an excuse to go think).
Plus, the psychological part can get you later even after you think you've quit. Business trips (especially to foreign countries where no one speaks your language) always cause me problems. But, I never smoked after I got back home. I also smoked the whole year I spent on a remote assignment in Alaska. In fact, being left at home alone without any of the kids to keep me company can get me started again unless I find a lot of things to do to keep occupied. (For someone who's always been pretty quiet and private, I was kind of surprised to find I had so many problems with being alone.)
Cigarettes are a little like heroin, except more addictive. Eventually, you quit enough times, you get pretty good at quitting. Maybe good enough that you spend more time as a non-smoker than as a smoker.