I have a post here about how I quit, but I'll give you the TL;DR version:

I set one rule: smoke as much as you want but only three from each pack I bought. Then the pack had to be thrown away - destroyed completely and thrown away. If I wanted to smoke more, I had to buy another pack. That became very expensive for a while but it got me down to where I could quit for good. And I did, in 1995.