The square face has a wide, angular jawline and for head; the lines of this face are straight and angular. I find this face shape to be rather sexy. Something about the strong jawline is extremely hot to me.
So with the square face you want to avoid harsh strong lines like blunt fringes, blunt bobs and short tapered hair. Since the square shape face has strong angular lines you want to avoid adding more severeness to the face shape. You also want to avoid angled cuts hitting the jawline as it will only accentuate the straight line of the jaw and create width in the jawline and cheeks which will make the jaw appear to be larger.
Hairstyles that work best for the square shaped person usually are softer cuts. Try wispy ends or a soft side swept fringe that cuts into the square face. Also, go for a lot of layers so it gives your appearance a softer look. If you want to try a short style, go for a softer pixie cut with lots of texture with not too much volume on the sides.
This works because her layers on top are full of texture and she styles it tousled so it doesn't look harsh on her face.
See how Demi's soft wavys doesn't bring attention to her jawline.
This really works for Kiera, it cuts into her jawline making her hair appear to be less square and more oval.
This length works out really well for Olivia.
I don't care for this hair cut on Paris, but I posted this photo because it really shows her strong square face off.