One of our favorite Photoshop tools is "Dodge" and "Burn." These tools are extremely powerful and can be used in a variety of ways. Often times in order to play with the light in the photo, we will dodge and burn the photo to emphasize/minimize highlights/shadows (especially for photos receiving B&W treatment).
For this particular photo of a good friend, we've decided to add digital makeup using the process of dodging and burning.
BEFORE
AFTER