The cut is the smallest action in smoking a cigar and the one most often done badly. The goal is to open the head enough for a clean draw without compromising the cap, the small piece of wrapper that holds the rolled cigar together at the head end.
The conventional method is the straight cut. Use a sharp double-bladed guillotine cutter (the cheap single-blade ones tear the wrapper). Hold the cigar with the head facing the cutter, place the cutter just above the cap line where the wrapper finishes, and close the blades in one decisive motion. About an eighth of an inch is enough; cutting deeper into the cap risks unravelling the wrapper as you smoke.
The V-cut creates a wedge-shaped opening rather than a flat one, which concentrates smoke at the centre of the cigar. It works particularly well on Torpedos and figurados where the tapered head benefits from the wedge geometry. V-cutters that go dull, however, crush rather than cut.
The punch cut bores a small circular hole through the cap rather than removing material. It produces a tighter, more concentrated draw and is forgiving for cigars where you are unsure where to cut.
The one mistake that ruins cigars: cutting too deep. Once you cut below the cap, the wrapper has nothing holding it in place and will unravel as you smoke.
For more on cigar construction and the parts of a cigar, see The Anatomy of a Cigar.