I find that the application of the dark undertones first - in this case a mix of ultramarine blue and transparent red oxide - in a thin wash, and then an overlay of cerulean and white for the lighter areas works wonders in creating the look of sun-washed skin. I see that the symmetry is off a bit in the eyes and nostrils, but rather than muck with the transparencies I will move on to another painting.
Endless days of heat and sun and projects to do has left little time for making headway in the painting game, but I find myself curiously looking forward to winter. That's a first!