First off you have to want it, I mean really want to quit. Second take it one hour at a time. Make a promise that you wont smoke for the next hour... and then the next and so on. Things will get better after a couple of days, it wont be as hard. I know this sounds nuts, but smaller goals are easier to keep
I quit after 30 years. Do something different at the times/places that you normally smoked. Start a new hobby. I like sanding and painting old things. It makes you accept that you used to smoke during this time and now you do something different. The first 2 weeks are the hardest. Then after 2 months you feel a big relief that it's history. Go for it. Just do it. You can do it.