Body motion for haircut

Haircut Tutorial: Body Motion for the haircut.
When we do the haircut, we use the straight line to make a hairstyle. But when we stand still to move the finger, hand, arm you will make a part of the circle movement, not straight action,
Any times you make a straight line, we use the ruler to make the line, haircut we don’t use ruler, that why haircut is hard to make,
if you use your body movement to make a straight line, you can control to make a straight line