You need to identify every reason you smoke a replace the cigarette smoking with something else. Like every time you get the urge to smoke because you are stressed you go for a walk instead. Or if you are bored then you find a hobby to do. Do this for every reason you smoke.
Also, make it harder for you to smoke. Like buying the smallest size pack. If you do this then you'll force yourself to out and buy a pack every time you run out. Another one is to pledge that you will never smoke inside so you'll need to go out every time you smoke. I would also keep my pack inside a cash box, or something similar, with a combination lock. Again, you want to make it difficult to smoke so that it becomes a hassle to smoke so you think about why you are trying to stop and it stops being an automatic function.