I quit with the help of Zyban, and it worked. I quit smoking about 25 years ago and not a single cigarettes since. After 30 years as a serious smoker.
I was the worse kind of smoker. A romantic smoker. Like even death would be a celebrated event if John Wayne held a lit cigarette to my lips as I took one last puff as I ascended into heaven. Like the joy of witnessing sunrise and sunset were ramped up 10-fold by lighting up.
Step 1 - plan to quit, not just to slow down. List all the reasons why you want to quit and list all the obstacles that will sabotage you if and when you do quit. Get all this out front and well in your awareness well before you pick your quit day.
Step 2 - convince yourself that "just one" is a lie. Just one will just make you cough and feeling empty, in need of more to thoroughly fill your addiction. It might take an entire pack of cigarettes to get back that feeling, but "just one" will be the gateway.
Step 3 - at the beginning of each day, convince yourself that the most important thing that you will do that day is to not smoke a cigarette. If you later think your need for a cigarette is interfering with your life, it's not. What's important is to not smoke. Everything else is less important.
Step 4 - take a mid day break to explain to yourself why you are no longer a smoker.
Step 5 - at the end of each day, have a serious conversation with yourself about how all those urges to smoke were simply tricks by the addiction to undermine your love for yourself.
Step 6 - take your achievement and success to bed with you. Pat yourself on the back. TOUCHDOWN. You 1 - Addiction 0.
Repeat the above daily for the next 30 days. The next 30 days will be easier. And easier again for the next. If you still feel like smoking after 90 days without, tell yourself that you will consider smoking again when you celebrate our 85th birthday.
The above is a bit easier with the the help of anti-compulsive behavior drugs like Zyban or Wellbutrin ... drugs that give one a bit of an edge in overcoming compulsive behaviors.
Hang in there. Quitting smoking is about self love.