Creating Glossy Lips
If you see a shiny highlight on your subject’s lips, and you want to make it look glossier, duplicate the Background layer then change your layer blend mode to Screen to brighten the entire image. Option-click (PC: Alt-click) the Add Layer Mask icon to hide this brighter layer behind a black mask. Press D to set your Foreground color to white; choose a small, soft-edged Brush (B); and paint over those white highlight areas on the lips and they’ll get even glossier.
by Scott Kelby