How do you quit smoking after a long time?

Whatever works 4 you. There are many short and long term benefits from quitting smoking. In addition to nicotine substitutes and certain medications, changing your habit patterns around triggers to smoke can be challenging. Getting support from friends, family, co-workers and community resources are all helpful. Understanding why you smoke can help you find better choices to redirect those urges. Good luck!
Make a plan. Many people quit cold turkey; others taper off. Whatever you do, have a plan. Check out free smoking cessation programs online, like american lung association, or contact your state's free quit line. If you quit cold turkey, set a date. Beforehand throw out all your smoking stuff. If you need help, ask your pharmacist or doctor about medications. It usually takes more than one try. Don't give up!