It is hard, but you can do it if you really set yourself to it. First of all, you really genuinely need to want to quit, not just think that you ought to, otherwise you won't be able to do it.
I've found nicotine gum quite useful, it keeps the edginess away and fixes the urge when you are drinking in a bar and everyone else around you is smoking. Other than that I try to have something to nibble all the time, grapes are a good one. Something healthy though, or you will gain loads of weight.
I've gone on a break a dozen times already and even after months of not smoking it is so easy to fall back into the bad habit. Now I've quit again, 2-3 months ago, and although I occasionally bum a cigarette in a bar I don't consider myself a smoker anymore. I won't pick up smoking again, it just isn't enjoyable anymore.