Find your face shape by measuring (tape or ruler) across the center,
edge of cheekbone to edge of cheekbone. Then measure the widest point
of your jaw. Do a similar measurement for the widest point across your
forehead, which is usually halfway between your eyebrows and the line of
hair. Finally, measure from the bottom of your chin to the start of
A round face, the good old pieplate cheery face, has equal length to width, or at least very close. Compare the cheekbone to cheekbone measurement with the hairline to chin measurement. Fuller and higher hair will adjust the appearance of dimensions, giving you a narrower look. The sides can be kept longer and flatter to make your face appear more oval. Avoid the page boy that widens at the sides and chops below the chin, or this will complete the appearance of a pie-plate face. It's okay to smile, but don't go around looking like the man-in-the-moon, with a big grin all the time. (You're doing it again. Stop that!)
For the oval face, the length is greater (about one and a half times), with the forehead usually wider than the chin, and the face tapering to the narrow chin. This face suits most hairstyles - you can basically call the shots. Watch out for a heavy drapery of bangs, as this makes your face look heavy, and covers up the elegance of the oval.
The extreme version of the oval is the heart-shaped face as frequently portrayed by Japanese Anime with the wide eyes and forehead tapering to a pointed chin, giving that Pixie look. Short hair, either chin-length bobs or short shags, complete the cute look. A few bangs can assist, but don't raise the hair and leave too much weight up top, or the face will be unbalanced. It'll be like looking at a top.
With the oblong face, the length is slightly greater than the width, but
the width measurements are almost equal (cheekbones, jaw, and forehead).
When the chin is prominent, this can be most impressive. Many styles
are possible, though when the jaw is prominent, the hair needs to be
longer or fuller. A shortie style will look odd. Too much length could
make your face look longer, so you are really attempting to get some
layering and fullness at the side.
The diamond-shaped face has a narrowed forehead and jaw width, with the greatest width at the cheekbones. Adjust your head to give some weight to the top, and smoothing down to the cheeks. The jaw is already narrow. Mostly, keep the hair short with fullness at the temples. You can also experiment with shags and off center parts, making sure you've left enough layers to expand the upper part of the face. Avoid fullness at and below the jawline.
The square face has equal width to length, with the jawline squared. No, this doesn't make you a blockhead, as it is the position of the eyes, nose, and lips that defines the beauty. Hard work is required here to avoid that tough look. Try for waves, curls, soft bangs, anything that can soften the edges. Watch out for long straight hair with blunt bangs to avoid magnifying the square look.