Alan Carr's Easy Way To Quit Smoking will always be a great suggestion. People we're giving that recommendation out 10 years ago on here and still are for good reason.

Other than that, there's something about nicotine addiction I had to discover for myself that maybe wasn't in that book. It's that you should try to replace nicotine with something else. Not another chemical substance necessarily, but a new habit in general. I've had luck with exercise and language learning myself. Being able to associate sobriety from nicotine with something actually beneficial helped me feel doubly convicted to stick to a quit.