Banning it.
I'm not even joking. If your only goal is to lower consumption rates, prohibition works. If you use cirrhosis deaths as a proxy, then alcohol consumption declined during the Prohibition era. [1]
The problem, of course, is everything else that happens in the wake of enforcing it.
An alternative option is to do nothing, because it's kind of a bikeshed issue, anyway.
[1] http://pubs.niaaa.nih.gov/publications/arh27-3/209-219.htm
You have to show ID to purchase tobacco products. They even have signs at some convenience stores which say the year you must be born to purchase tobacco products, which the year is the current year minus 18.
Stop changing the cutoff year. This will allow the current generation of tobacco users to continue, but ban future generations from it.
I'm suspicious, mostly because it goes against the conventional wisdom that alcohol consumption increased during prohibition.
Hardly unbiased sources, but....
http://www.druglibrary.org/prohibitionresults1.htm http://www.druglibrary.org/schaffer/History/e1920/chicagodea...
Be careful with this... It is the vapor salesman's false pitch. Nicotine is a known neurotoxin, it increases inflammation, lowers your hdl, raises your ldl, and stresses your endocrine system (adrenal et al.). While ecigs may deliver fewer toxins than analogs, that doesn't erase the fact that you are much better off without nicotine.
Unless there's a demonstrable, important (life affecting) effect, I wouldn't care too much about nicotine. Maybe some people are even naturally balancing some of their brain chemistry with it.
I wouldn't surprised if in 30 years we 'discover' that nicotine was okay all along, just like eating fat.
By the way, what is your opinion on caffeine?
I miss the neurostimulant effect badly... if you are right about nicotine being exonerated, I'll jump for joy and pick some up that day.