All you need to do is leave it sitting on the edge of the ashtray or tip it in and leave it be. This is the correct way to extinguish a cigar. When you leave it for dead, it may continue to smolder for some time, but it will be a very modest amount of smoke, until it subsides completely. The single greatest mistake, and a considerably inelegant way to put your stogie out, is to grind it out as though it were a lowly cigarette. Cigars are refined, and dignified, deserving an elegant and regal farewell. Leave it in silence and it will slowly fade into a fond memory of a great blend. Try to snuff it out, Marlboro man style, and you are asking for a smoky disaster, more like a brush fire rather than the last breaths of a premium stick.