Like with so many things in life, practice makes perfect. While single- and double-bladed guillotine cutters are rather straightforward, cigar scissors take a bit more practice. While scissors are arguably the most elegant of all cutters, they are also the most difficult to master.
To start, you place your thumb in the circular hole on one of the scissor arms, and, depending on what model of scissors you have, you put your index, middle and ring fingers in the large and curved opening on the other.
Next, open the jaws of the scissors, place them at a slight angle to the head of the cigar, and close the jaws very slowly, bringing the cutter perpendicular to the top of the cigar as they close. The result is a clean, impressive cut. It takes a few tries to master the motion.