Zevo has an imperfection .Psd overlay MR over at Daz, there's also a ton of various .abr files for free on the web to modify, retouch, and paint skin. Also, look at reference and paint your own for that "hand made" feeling. Really, one of the easiest texturing things to achieve... just make sure to do all of your overlays on a new layer.

Edit_ don't forget, you can also create your own custom brushes and fill patterns.