Beards can serve many purposes; a man may grow a beard to make a fashion statement, to hide scars or other facial markings or to complement the structure of his face. A properly cut beard can also serve to make your face look thinner. Beards that accentuate the vertical lines of the face can help a person with a large face, a round face or chubby cheeks create the illusion of a relatively thin face.
Grow sideburns, if you don't already have them. Well-maintained sideburns with clear and straight edges that connect to your beard can help create the illusion of a thin face. Keep your sideburns neat by trimming them frequently with facial hair scissors.
Shave your beard into a squared-off shape with an electric shaver or a manual razor. The edges of the beard should be straight, and it should have defined corners. Trim the beard with facial hair scissors so the hair is no longer than 1/4 inch.
Shave your beard into a triangular goatee, if you prefer it over a full beard. Make sure the center line of the goatee lies in the center of your face. The triangle shape of the goatee will accentuate the verticalness of your face and make it appear less round. Keep the goatee well-maintained by frequently trimming it with facial hair scissors.
Consider getting a haircut that is longer on top than it is on the sides and temples. This hairstyle can help make a round face look thinner. Nearly any type of mustache is flattering for someone with a large, round face because it diverts attention from the roundness of the face and makes people focus on the center of the face.