Basically section from ear to ear, like the 'hot cross bun' (i feel its more professional to call them quarters, we're not bakers[emoji23]) just without the middle part.
Apply to the section, now start in the crown in a brickwork technique down to the nape, once the backs done, start at the crown again working towards the hairline in a brickwork fashion, sugarplumfaery will probably be able to explain it better than me!