To cut short layered hair, use an eight-guard hair trimmer to trim the back of the neck, and take half of the hair and clip it back. Next, trim the loose side with the eight-guard, following the line of the head from back to front.
Release the clipped side, and take a 1-inch section of hair from the trimmed side to compare the length. Begin trimming the uncut side with scissors. Be sure to cut the hair at an angle instead of horizontally to avoid a blunt edge.
Once you have trimmed evenly, blend the sides into the new length in the back. Taking one 1/2-inch section at a time, hold the ends parallel with your fingers, and cut at an angle to blend. For hair at the crown, take sections of uncut hair, and mix them with cut hair. Pull the hair above the head, and point cut with the scissors to blend. Blending should make the layers look even.
As you near the front of the head, pull pieces toward your face that are mixed with pieces that have been blended. Cut upward first, repeat the same method as the crown pieces, and then point cut. Pull pieces out with your fingers to check the length, and trim whatever small pieces are too long.