✅ Preservation of human anatomy is the main task for natural retouching.  I remove hillocks, skin folds, wrinkles, flabbiness and swelling, but not bones or muscles. Some areas are only slightly smoothed out to make them look better, such as nasolabial folds or areas under the eyes. But I never completely remove them because it make the face looking fake.
✅ The smoothness of the gradients and the preservation of highlights and shadows - I try to remove mid-frequency spots which contaminate the picture without making the picture flat. The highlights should remain highlights, the dark areas should remain dark.
✅ The texture shouldn't suffer - I try to do d&b without zooming too much to not blur the texture of the skin, most often I do d&b on 30-50% zoom of the picture.
✅ I usually work on a 50% gray Soft-Light-neutral color layer, but sometimes I use Curves if I want to achieve not only lightening or dimming but also adjust contrast, hue and saturation on the edited area.