Measure, do not eyeball
During mapping, use thread or callipers from the facial midline to matched points on each side (bow peak, commissure, fullest point). Record the differences. Decide with the client which are worth minimising and which are part of their face.
Tools available to a blush
Colour illusion: slightly higher shading density or a faint highlight-halo on the smaller side makes it read fuller. Border nudge: placing the border a fraction outside the natural line on the shorter side — one to two millimetres at most — evens the visual line. Value: keeping the deeper-coloured side a touch lighter balances perceived size.
Honest limits
Marked asymmetry from volume loss, a scar, or a neurological cause (uneven smile) is a structural problem. Blushing helps a little; filler, or nothing, may be the better answer. Say so rather than over-promising with pigment.
