1.  If your face is ROUND . . . look for sunglasses with rectangular frames, because they add definition to your face and make it look longer and thinner.  Circular frames do the opposite and just make your face look even rounder.

2.  If you have a SQUARE face . . . go with something round or oval-shaped.  It's okay if they're flat along the top of the frames.  But the bottom of the frames should be curved.

3.  If you have an OVAL face . . . you're lucky, because pretty much any type of sunglasses work.  An oval face usually means you have a narrow forehead, a narrow jaw line, high cheekbones, and a narrow chin.

4.  If you have a HEART-SHAPED face . . . meaning a wide forehead, narrow jaw line, and a narrow chin . . . choose frames that are bottom-heavy, like aviators.

Or if you're a woman, look for cat-eye style sunglasses that are round on the bottom and come to a point at the outer corners of the top.