Well done for trying Peppy. I have tried to quit numerous times, and failed miserably on each occassion until I fell pregnant and the choice was taken away from me then really - I CAN'T smoke because of the baby.
What I have found to help though is, as Peppy points out, setting realistic targets. I used to find that if I told myself I was allowed one cigarette every evening at, say, 8pm then I would not have cravings the rest of the time because I knew I was "allowed" one later. I also didn't punish myself so much for breaking, eventually when it comes around to 8pm, I would think I;ll see if I can go til quarter past without, then half past, then quarter to nine, etc - then all of a sudden it's bed time and I haven't had a cigarette for a whole day! The next day you feel realy proud of yourself for not having one, and the NEW cycle starts again.
Another thing I found to help was to ban myself from smoking during certain times (my favourite cigarette was the first when I got infrom work at around half 5, and so would ban myself between 4 and 6 for example) or in certain areas.
Good luck, and remember we are all here to help you if you feel you're going to crack!