When I first started looking into skin retouching for my portraits, I had frequency separation tutorials (written not video, unfortunately!) fired at me and I went about learning what that technique does and how to use it effectively. Within a few years — and sometime after I'd really put the hours in to master it — I was then told it was awful and I should never use it again.
The truth was and is this: as with most techniques in photography, too much will make your images worse. Many people were using frequency separation to blast past the removal of blemish and the smoothing of skin, and into the realms of a textureless uncanny valley. This garnered the technique some negative press, but it has remained an effective method for skin retouching if you use it in moderation.
In this video, Unmesh Dinda from PiXimperfect goes through frequency separation using the new tools in Photoshop and how much better, easier, and quicker it has become.
-(written not video, unfortunately!)
The opposite. Please get back to written descriptions. Videos suck on almost all fronts.