This eyebrow shape for your face with rounded arches will help bring more balance if you have a angular features. See how the more rounded lines soften the model's angular jaw line. If the brows were more angular or pointed then it would accentuate her face shape.
Remember, you only want to take any hair that's outside your shape on top of the brow. (For more help see: Should I Tweeze the Top of Brows?) So be careful when trying to make rounder lines. But, you can always 'fake it' with eyebrow pencil like Billion Dollar Brows Universal Brow Pencil (buy direct). It's formulated to work with all skin and hair tones, so there's no guesswork in picking the right color.