Tutorial: Contouring

Let's start with an image that is edited and just needs a little something to make it pop. Select your burn tool on low opacity (adjust to taste) and set to shadows.

These are the areas I burned.

Then you select your dodge tool, low opacity to taste and set on midtones.

These are the areas I dodged

You can also do it on faces to add more dimension.

The black areas I burned, and the white I dodged.

Enjoy! Feel free to post links to your images that you have used this tutorial on :)