First off, you got want to. Like seriously, want to. There's people who are "quitting" because they say they want to (just to appear like they are trying) and people who genuinely want to quit because it's expensive / bad for their health / etc.
Quitting outright like you are doing most likely won't last (don't get me wrong, everyone has different ways of quitting), but something you should try is count up how many cigarettes you smoke in a week while not trying to quit. Let's say, it was 50.
Break that down per day, that's about 7 per day. Each week lower it little by little.
Week 1: 50 or 7 / day
Week 2: 42 or 6 / day
Week 3: 35 or 5 / day
Week 4: 28 or 4 / day
Week 5: 21 or 3 / day
Once you get down to 3 per day, it gets harder to cut out "x per day". While tobacco/smoking is certainly addictive, alot of reasons people do it is habit. Habits they don't realize. For example, you're probably used to lighting up one after you eat. You don't NEED it, you're addiction isn't even kicking in...you're just used to it and the habit kicks in. Try and knock these.
Another thing is, in all seriousness, it may be wise to purchase an e-cig of some sort. They can also help, because if you're getting that craving you can always turn that puppy on and hit a drag or two and be done with it.
I'd personally recommend once you get down to the 3 / dayish mark start substitution that way...hit an e-cig x number of times, for x number of times per day, which would be equivelant to 3 cigs...then bump it down to equivelant of 2.5 cigs...then 2 cigs...once you get close to this point, you'll start feeling a little better and probably will be able to quit after that with relative ease!