In this video tutorial, Aaron Nace from PHLearn.com show a great technique that allows you to re-touch portraits without turning the subject into a porcelain doll. The techniques smoothes out the tones in the subject and leaves the skin textures intact. You can retouch both the tones and the textures as two separate components and have the resulting image appear smooth, yet real.
If you retouch protraits often or want a fast way to get started, they also provide you with a photoshop action that you can download.
IMAGE Credit: Aaron Nace from PHLearn.com