[header] How to buy sunglasses [title] Choose a frame shape that contrasts with your face shape. [step] That way your sunglasses will balance out your face when you're wearing them. Wearing frames that match your face shape may accentuate the shape of your face, and they won't pop as much. 
[substeps] For example, if your face is more round, you could choose a pair of square, angular frames as a nice contrast. If you have a squarer face with a defined jaw, sunglasses with round frames may help soften the angles of your face.