Thought I would post my favorite retouching trick that I use a ton:

1. Duplicate layer

2. Change blending mode to Soft Light

3. Image > Adjustments > Shadows/Highlights (i usually leave it the default)

4. Filter > Other > High Pass (usually use a radius between 2-3.5)

Don't know if this one is common knowledge but I think it's a good one :) Feel free to post your tricks as well.

cheers