Some tidbits from a close friend who tried to quit for years before working with a hypnotherapist who also gave her some great pointers:
-Think of yourself as a non-smoker. BE a non-smoker.
-Where do you usually smoke? Take away all the ash trays. REplace them with things that keep your fingers busy- she put a basket of knitting next to her old smoking chair, and moved it away from the window so she couldn't cheat and flick ash outside.
-If you tend to take breaks from work just to go smoke, find another thing to do on your break, like take a walk around the block, or go make yourself the perfect slushie down at the quick-E-mart, or go hit on that hot new receptionist who wouldn't talk to you before because you stank smoke.

And don't forget to enjoy how much better the world will smell and taste to you once your senses have recovered from the layer of ciggy-gunk!