The basic rule is to maximize your fit, style, and comfort by choosing a collar based on the shape of your face. There are 3 basic face shapes: Angular, Oval, and Round. If you take a look in the mirror you should be able to identify which shape belongs to your face. If you’re having trouble, ask someone else for his/her input.
Angular (Triangular, Narrow, Long)
If you’re tall and/or thin you may have an angular or narrow face and it’s best for you to look for a spread collar—low and wide. Avoid a straight collar. A spreadcollar will soften angles or visually shorten a long, narrow face.
If you have a round face and/or short neck, you will want to choose a straight collar —long and vertical/ pointed. Avoid spread collars. The vertical point of a straight collar will visually lengthen your face.
If your face is not round or angular, it is likely an oval shape, and most types of medium length straight or spread collars will work well to balance out your face.