If you have a diamond shaped face, you should look for cat-eye glasses or oval frames. These frames will play up your narrow forehead and chin and accentuate your cheekbones. Avoid loose or narrow frames.
If you are square shaped faced, look for eyeglasses that sit high on the bridge of their nose and have oval or round frames. You should avoid angular and boxy frames that will draw attention to your square face, go for round glasses that will help break that square shape.
Choose a frame color that complements your skin tone or eye color. Your skin tone should take precedence, rather than your eye color or your hair color.
Other factors to consider when choosing your glasses include your eyebrow, hairstyle, make up, wardrobe style and personal fashions style. Cat-eye frames would work well for a vintage style, semi-round frames works best for a preppy style environment. If your style is more vintage and a little alternative, you might choose glasses with a round rim, but for an executive look, you might choose a square frame. Conservative frames are often the best choice if you are working in a serious business environment. Oval, rectangle, and almond frames work well for a professional style. Avoid frames in bright colors or unusual shapes unless you work in a casual environment.