For a square face creating softness is the idea. This means texture curls and some spiky short cuts. A square face can also be played up and used as a strong statement. Short sleek styles work beautifully for this.
Avoid
Blunt cuts and blunt bangs if your trying to soften the squareness, if your trying to have fun and be dramatic than those are the lines to go for.
A good example of a sqare face is Gwyneth Paltrow.
Other face shapes.