Hair should be dry when using thinning shears. If you use them on wet hair, you may not realize how much hair you are cutting off. When the hair dries, it may be different than what you wanted in the first place. If you are using it to blend, be sure to dry the hair, then use the thinning shears to blend layers. Be sure that the flat edge of the shear is on the bottom and the teeth are on the top.