If you've ever used luminosity masks, you know how perfect they can be for creating specific looks, effects and styles, and are also hugely purposeful for specific utility processes in your workflow. There are many ways to go about creating luminosity masks, but have you considered simply using the Gradient Map adjustment layer for this?
Let's face the facts and admit that frequency separation is quite likely the most misunderstood and misused retouching techniques, plain and simple. If you've never heard of frequency separation, then do yourself a favor and browse YouTube on the subject before reading on.
If there is a question I get asked the most about my retouching approach in Photoshop, it's: "how do you achieve your skin tone?" While I, of course, appreciate the acknowledgement, I also wondered how I could create an action in Photoshop that would help me streamline my usual skin tone workflow. After a while, I came up with something I thought worked well and decided to give it away to you. Check it out!