Whatever method you choose, you need to prepare yourself emotionally to quit.
Make a list of pros and cons that examines how smoking enhances your life and how it detracts from it. A realistic and comprehensive list of pros and cons will almost certainly show you that continuing to smoke is a really bad idea, and that a rational person would want to stop. That's obvious to most people, but if you think you might want to quit, you should reflect on everything that is unpleasant and harmful about smoking until you decide you don't care or you develop a strong desire to quit. If don't have such a desire, you can have quit-smoking aids sticking out of every orifice, nicotine patches stuck all over you and hypnotists following you around everywhere you go, and you will still fail.
Understand that there are two components to nicotine addiction: the psychological component and the physical component. The psychological component is the habits and routine you have built around smoking, and it takes a long time to go away. For some people, it never really goes away, and there will always be times where they will feel a slight nagging like something is missing. The physical component is the body's dependence on nicotine, and this takes much less time to go away, but its effects are painful and difficult to withstand. It takes at least 3 days for the body to rid itself of nicotine and dispense with the physical component, during which time most people feel physically ill, anxious, restless, angry and so tempted to smoke that they have to restrain themselves from lunging at passing smokers.
The initial 5 days of craziness is the general rule for just about any quit-smoking method, but the 5 days are particularly painful if you quit cold turkey. The psychological and physical components of the addiction work on you day and night, and it can be really difficult not to smoke.
Pick the right time to quit. For example, if you are a student and you are about to have final exams, you should probably wait until after you've walked out of your last exam and partied your brains out that night before you settle down and quit. Look at your calendar, think about what stressful events you have coming up, and pick a day that leaves you at least 3 weeks between major crises. You're going to have to deal with crises all your life, and this will not change after you quit smoking. However, it would be best to have a relatively smooth patch of 3 weeks or so to get over the really rough initial quitting period. You must not use this as an excuse to never quit; we're talking major stress-filled events here--like quitting a job, final exams or planning a wedding. If you find yourself "waiting for the right time" more than once, or for more than a couple of weeks, you're stalling.
Pamper yourself. In order to boost your resolve, treat yourself nicely in return for not smoking. Spend the money you would otherwise spend on cigarettes on something that you've always wanted. Take yourself out to nice restaurants that don't allow smoking. Feel better about yourself, because you've taken steps to improve your health.
It's also a good idea to begin exercising, because if you have a good exercise program going, it makes you feel a lot better about yourself. If you're getting up at 7 a.m. to go to aerobics before you go to work, you're going to feel ridiculous counteracting your hard work by smoking later on in the day.