Natural Looking Retouch in General
Any retouching images will be good if you are able to keep people looking natural. However, only looking natural does not mean you do not use any effects in it. In addition, it looks good if you use different effects to freshen them up and reduce the harshness of the precise lens. Any retouching images will be look natural if you kept the skin texture in and the soft hair on the face.
Most important part of natural looking retouching is the glow it gives the face. If it shines, it looks really lively and very natural. Moreover, everyone loves the natural look of an image. Therefore, before doing any kind of retouching, you have to keep in mind about the natural fact which is- people love to see natural look.
Practice more and more at home in order to success in this kind of retouching. Practice more and succeed. Happy Photoshopping!