6 Enhance eyes

To boost the eyes, first add a Curves layer, lift the top of the line and pull down on the bottom left (in a similar way to tip 1) to boost the contrast. Press Ctrl/Cmd+I to invert the mask to black, which hides the effect. With the layer still highlighted, grab the Brush Tool and paint with white to reveal the tonal change over the eyes. Lower the strength of the effect by dropping the layer opacity slightly.