A full beard has a very distinct shape: It starts at the cheek line and everything below that is left to grow naturally.
Beardsmen who have cheek lines that are naturally too high, or have trouble defining the cheek line, are advised to draw an imaginary line from the angle of the side burn in front of the ear up to the outer edge of a mustache.
A full beard takes time and it’s recommended beardsmen who want this style start growing their beards while on leave to get past the first phase. There may be strange reactions from other people during the growing phase.
After 4 weeks beardsmen who are successful in growing a full beard can start shaping it and start defining a neck line.
For this process a professional stylist or barber comes highly recommended and can usually spell the difference between success and failure.