In order to cut hair in a layered bob hairstyle, work with a 1-inch section of hair at a time and clip off other sections, use tension with fingers and a comb and cut sides and back of hair in a basic bob shape and add layers to the top sections of the hair. Comb the hair in the manner desired and make certain the length is equal on sides and back and in all layers.
Detangle and comb hair back as if tying a pony tail at the nape of the neck. Part hair down the middle from the front forehead to the back nape and section further by parting hair from ear to ear. Clip each section while leaving loose the back two sections closest to the part. Using tension, pull a comb through this section of hair to desired length and cut straight. Continue with other back and side sections so all hair is the same desired length.
Release the top hair from clips and starting with a 1-inch section of hair from the middle part, comb and cut the hair as before to add a layer that is somewhere between the back and front length. Continue to section off and cut top layers until the top sections are uniform, giving a layered bob effect.