Skin softening

Open up a portrait image in Photoshop

Duplicate layer

Top layer filter-convert for smart filters

filter-blur-surface blur (you could use gaussian blur but there is a bit more control with surface blur) - use a radius (amount of blur) of about 10-15 and threshold of about 35 then reduce opacity if you have overdone this.

Select the mask that has been created and CmdI to convert it into a black mask.

Use a white paint brush and paint over any areas that you want to soften reducing opacity of the paint if required.