First, be sure you have a good quality cutter with a very sharp blade/s. You only need to shave off from 1/16" to about 1/8" of an inch, no more. The idea is to try and keep the cap intact. If you clip most or all of the cap, as you smoke the cigar and the head becomes wetter, it will open wider and the cap will very likely peel off entirely. Some smokers don't mind if this happens, but others find it sloppy.