Things You'll Need
First and foremost, you have to want to quit smoking in order for it work long term. If not, you'll find a reason to start again.
Pick a three week period when work or school is going to be less stressful. Summer break, the holidays, a vacation are all possibilities. You most likely smoke more when you are stressed, so eliminating the stress is a good place to start.
This three week period of time should also be a time when you can step away from alcohol. For most smokers that drink, these two go hand and hand. Trying to quit smoking while continuing to drink alcohol will make it significantly more difficult.
Get in a healthy mindset. Start exercising more during this time
and make an effort to eat healthy. This is hard because you might feel sick from withdrawal during this time. A large part of quitting is mental, so getting into a healthy mindset is essential.
Change your daily routine. Adding exercise and healthy eating is one way step. Reading instead of watching tv is another idea. Anything that makes the initial quitting period feel different is a positive thing.
Drink lots of fluids, especially water. There is a good chance you might feel sick, so staying hydrated is essential.
Finally, make sure your friends and family are aware of your decision so that they can support you. If certain friends used to smoke with you a lot, tell them not to smoke around you while you are trying to quit.