I quit about eight years ago. (2 1/4 packs a day.) Here are some things I learned in the process:
1. Quitting smoking is really learning to break a thousand different habits. You need to learn how not to smoke after meals, how not to smoke at the bar, after sex, etc. As silly as it sounds, you even need to learn how not to smoke in the spring, the fall, etc. Be prepared to deal with the cravings that arise in all the different contexts in which you normally smoke.
2. The odds are high that you'll fail in your first attempts. Don't get demoralized if that happens; it's extremely hard to succeed. Remember that even if you fail twenty times and succeed once, you win.
3. Resist the temptation to negotiate with yourself. For example, "I'll allow myself a cigarette if I have a bad fight with my SO, or if I have a tight deadline at work." If you do that, you will cause a fight with your SO or procrastinate at work so as to give yourself a tight deadline. In other words, don't allow yourself a cigarette under any circumstances.
4. Write out a list of reasons why you want to quit. Put it on your refrigerator or some other place where you'll see it regularly.
5. Be aware that you will reach a point where you want nicotine so badly that those reasons won't mean anything to you. At that point you need to be able to say "I'm not going to have a cigarette, even though I can't think of a single compelling reason not to have one." Once you cross that threshold, your odds of succeeding increase considerably.
Good luck!