There's no need to repeatedly tap or flick a cigar's ash like that of a cigarette. Handmade cigars are crafted from long-filler tobacco, which holds a far longer and sturdier ash than a cigarette, whose ash flakes and end up in your lap if left to any length. Fiddling with the ash with too much force can break off the ember, or "cherry," of the cigar, which will leave you having to relight.
The best thing is to first have patience. Wait until the ash is about an inch long, or until you see a crack develop, before disposing of it in your ashtray. If you wait a very long time, the ash will no doubt drop on your shirt or pants or on the floor.
When it is time to ash, rest the cigar against the side of the ashtray and gently tap the end of the cigar. If done right, and at the correct time, the weight of the cigar should allow the ash to naturally fall off. If the ash is not breaking off, rest it on the side of the ashtray for a second, then repeat the process.
You can also gently press the edge of the cigar against side of the ashtray, turning or rotating the cigar at the same time. Take care not to press too hard. This will allow the ash to break off evenly, and you'll avoid any of the pitfalls mentioned above.