There's nothing quite as appealing as an oval face lightly framed by sexy, beachy waves. Jessica Biel proves the point in flying colors here. This medium-length hairstyle lets Biel's face take center stage with casual, unfussy waves and long, sexy bangs draped seductively across the forehead. A center part works great, too, if you want to be a little more understated.

While this is a terrifically chic hairstyle, it won't work on an oblong face. It's far better suited for square faces. The center part and long face-hugging sides go a long way to emphasize a long skinny face and high forehead. If you want your face to look even longer and skinnier, this is the medium-length hairstyle for you.

What a difference volume makes. This medium-length hairstyle creates the illusion of having the highly desirable oval face shape. Volume at the sides creates the illusion of fullness at the cheekbones. Bangs lightly dancing on the forehead reduce its dominance. Plus, we're pretty sure this look is the definition of "great hair."

We're not sure why Knightley would want to hide her stunning good looks with this afterthought of a hairstyle. But take it from us, if it doesn't look good on her, it almost certainly isn't going to look good on any of us. Hair that's above the shoulder needs to be kept simple and neat. These almost-waves might have worked on longer hair. The result here made us wonder if Knightley had cut her hair herself that morning.

This is possibly the perfect hairstyle. Nearly everyone on earth can wear it and look her best. This style is versatile, sophisticated, feminine and chic. To get the look, go for a shoulder-length medium cut with long layers. You can wear it stick-straight, or blown out (as seen here), or in beachy waves. It goes up in a twist or back in a pony in an instant, while the front layers automatically style themselves.