The chin strap is one of the most grossly misguided beard styles out there. It requires hard and precise lines that need constant upkeep, they do not grow out well and chin straps are unforgiving to mistakes and awkward characteristics. "The chin strap works best when it matches the line of the jaw, particularly on a strong featured guy," says Mike Sposito, Head Barber at FELLOW barber.
As a general rule, the wider and rounder the face, the thicker the strap should be, like Melky Cabrera; the leaner and more angular the face, the thinner you can take the strap (but don't necessarily have to – the style is a little dated). Expect to carve up those tight lines at least twice a week and keep the hair trim to the face – long chin straps veer dangerously close to the inimitable Abe Lincoln.