In my opinion, Dodge & Burn is the best technique in Photoshop. It is very easy.
But you need to understand where light comes from and how objects cast shadows. These aspects will help you to draw shadows and light spots in the right way. Otherwise, the balance of light and shades suffers a lot.

Retouching skin is a common talking point for photographers, as there’s a fine line between lustrous smoothness and the dreaded plastic look. An overly airbrushed image makes subjects appear more like children’s dolls than real people, and robs them of their humanity and charisma.

If you are not sure about the color of your skin, set the correct white balance. It's no secret that white balance is very important in photography.