This is a very quick and easy method which immediately enhances images.
1. Open your image in PS.
2. Duplicate your background layer (right click and select duplicate layer)
3. Filter > Blur > Gaussian Blur. The amount depends on the size of your original file. You want enough blur to lose the detail but retain the shapes and outlines.
4. Change the blending mode in the drop down menu at the top of the layers palette to Overlay.
5. Reduce the opacity to suit. Basically, this adds soft contrast to your image, so you may want to mask the effect out of skin tones and areas where the highlights and shadows become clipped as a result.