For a square face, incorporating an angle in the haircut is great. Doing side swept fringe would look good but avoid having blunt cuts, they accentuate the angles of the face and make it look harsher. Waves and curls also help to soften square lines.
Dramatic eye make-up can draw the focus upward to even out a square jaw line. Color – Darker colors recede, therefore if you’re self conscious about a square jaw, the color that frames your face should be kept on the lighter side.