Here the example how to retouch face of a girlfriend in Photoshop.
Step 1: Open you file with portrait.
We need to improve skin quality first. Try a took called Healing Brush. This instrument corrects imperfections, making the to be eliminated and smoothing surrounding area. As well as tools for cloning you may use this tool to insert sample pixels you have chosen out of your image or other pattern. Anyway, this tool matches lighting, shading, texture and transparency of sample pixels with pixels of the original source so repaired area looks organically with surrounding image.