I quit on December 28th, 2003 after smoking since I was 15. I got an upper respiratory infection on Christmas Eve; so for the next three days I couldn't smoke if I wanted to. When I got better I simply said "Well, three days, I'm done." and never looked back.
Social situations were and still are the worst. I still crave cigarettes when I'm in a social situation, almost three years later. I will occasionally have a cigar, but I don't inhale, and it's mostly for the smell and flavor and the "motion" of smoking cigarettes. But I only have a cigar maybe two or three times a year.
Just keep yourself cool in social situations and you’ll be fine. Find something else to do to keep your mind off of it.