Oranger, Welcome to XNations!
The way to stop smoking is the same as the way to stop doing anything else.
Humans are creatures of habit. Examine what you are doing when you get a craving for a cigarette, and do things to create a new behavior instead. If you notice that you usually go for a smoke mid-morning, and notice that your workload tends to lighten up at about that time, either use that time to do low-stress work, or to call a significant other, etc. If you replace the behavior with something else you enjoy, it will go much easier.