I actually am a smoker but in the process of quitting. It's ironic, because I use to be highly against it, even though I grew up around it most of my life. I picked up the nasty habit around the age of 17, I believe. But I hardly smoked then.. I quit for years, and then about a year ago I started going through some heavy stuff in my life, caved, had one and I was hooked again except worse than before.
It actually got so bad that I was at about 1-1/2 packs a day or more depending. And it's terrible for you, makes you feel like crap.. But it's also highly satisfying in the moment. For the past few months, on -average- I was smoking about half a pack a day. And now I'm down to about 2-4 a day. Which I suppose still seems bad, but if you've been a heavy smoker, you know how hard that is.
Ultimately my goal is to quit completely because I am getting older and it is effecting my health on a grand scale.
Any advice I could give on it is, don't do it, especially if you have addictive behavior. It's been very difficult to quit, and the longer you go, the harder it gets.