Purpose: Arguably, the most powerful feature of Photoshop is its masking.

Purpose: The Brush tool in Photoshop, in my opinion, is the most important and most used tool.

Purpose: Fix your pictures to have near perfect skin. Please note that beauty is in the eye of the beholder and you may or may want more or less of this effect.

In Short: Use black and white brush to draw image, then use layer styles to emboss it, then finally use some adjustment layers to achieve the look that you want.