I'd bounce with hopalong (do you see). Cigarettes (I presume you weren't talking about lighting up homosexuals) are addictive - this means that they trick your brain into making you think you need one. This makes you want one. Even though you definitely do not need them. So if you ever feel like a cigarette (even if you don't look like one) then you are becoming addicted.
I should point out that that was a bad joke and I am very anti-drugs. Just an ironic joke for which I am well known and at which Lindy Loo gets angry with me for.
I have to say from experience, cigarettes are very addictive.
It is very rare for anyone to just remain a 'social smoker' without addiction setting in at some point.
And once you are addicted, it is VERY difficult to stop.
Better never to start in the first place, and save yourself 10's of 1,000's of � over your lifetime.
A straightforward answer to your question is ONE. You are so likely to try a second after your first, then another until you crack just how to inhale properly etc...please don't even try it. You can also STOP after only one, or even a few if you are strong enough to beat this killer. I am a nurse and I look after people dying of cancer all the time..I work in a hospice. I know what I am talking about. I also got hooked on this silly habit 20 years ago, I still struggle. It isn't worth it, believe me.
Did you know that nicotine is more addictive than heroin. Giving up smoking is harder than giving up heroin. Unless of course you are very strong willed.