Designing a neckline for your full beard. More full beards are ruined by bad necklines than just about any other beard-growing error. Don't let your full beard be the victim of a bad neckline. Learn how to define a neckline that makes your beard look its best. Be sure to choose the right cheek line for your full beard, too. There is no single correct method for defining the neck line, but these guidelines should help you achieve a good result.