Selective lightening, darkening and localized contrast adjustments are essential tricks for enhancing the parts of the scene that matter most. There are lots of tools that allow you to do this, from the Dodge and Burn tools to Adjustment Layers and masks. But one of the simplest methods also proves to be one of the most effective. Click the New Layer icon to make a new empty layer, then set the Blending Mode to Soft Light. Grab the Brush Tool and press D to set your colors to black and white, then press 1 for 10% opacity. Paint with black to darken areas down, or white to lighten them (press X to swap between the two).