The square face shape is typically characterized by its strong jaw line, broad forehead and wide chin. The goal with a square shape is to make the face appear longer and soften up all those straight lines by adding soft lines and curves.
Look for frames with soft lines or curves such as an oval-shaped, round or cat-eye frame. Soft, curvy frames will reduce the strong angles of this face shape and give you more definition.
Narrow styles will minimize squareness and help lengthen the face.
The top of the frames should sit high enough on the face to minimize your jaw line.