How do I get rid of shine on people's faces?

If you look close at the shine on faces, you will see that this are extended specular reflections - the center of the shine is reflecting the lightsource towards the camera and therefore has the color of the lightsource. Towards the border of the shine this color is mixed with the dull reflection of the skin below the highlight. To get rid of this you need to brush away the color of the light source that is overlayed on the skin color, or if the light is white, make the glossy area darker and more saturated. You need a soft brush - weaker towards the margin of the area.

Regards

Léonie