(Fig. A) Hold a makeup brush parallel to the bridge of your nose to determine where your eyebrows should begin.  (Fig. B) Keeping the bottom end of the brush at the same point, move the head of the brush to the outer part of the iris to determine where the arch of your eyebrow should begin. (Fig. C) While keeping the end of the brush in the same place, pivot the head of the brush to the end of your eye. This is where your eyebrow should end.