One thing as a photographer you will always find yourself doing is retouching. It's an unavoidable part of the image making process and is vitally important to really get the best from your images before they are sent off to clients or published.
If you photograph people, be it during a wedding or a portrait session, one thing you are going to have to do time and time again is a spot of skin retouching. Even the most flawless skin, once scrutinised by the high-res sensors within the modern digital photography world, will show the odd blemish here and there and though you obviously don't wish to go overboard and completely change the features of your subject, you may agree that a little bit of perfecting here and there may be best for the commercial potential in your photographs. The purpose of this tutorial is to show to a quick and easy way to quickly retouch large areas of your subjects skin, saving you vital time, especially with larger shoots!
For the purposes of this tutorial, I am using the 2016 Edition of Photoshop, which is part of the Creative Cloud Suite (download a free 30 day trial version here), and Windows 10. Older versions of Photoshop or Windows may look a little different in appearance, but the fundamentals of this tutorial will be the same and the tools used are also available in most older versions of Photoshop.
As an example for this tutorial, I am using this studio image:
To start, I find it good practice to firstly tune up the exposure, colours and contrast in the image using the Levels and/or Curves tools (Ctrl+L and/or Ctrl+M are handy shortcuts for accessing these), as well as sharpening it up a bit using Unsharp Mask (accessible by following Filters>Sharpen>Unsharp Mask).
Next, in the Layers palette, duplicate the background layer by dragging and dropping over the 'New Layer' Icon on the bottom second right (arrowed). With your new top layer, change it's Opacity to around 75%, and change it's properties to 'Overlay' in the drop down menu.
You will notice that this will render your image incredibly high contrast; don't worry, once you've done a few more things you will see how temporary this stage was.
Next, select the 'High Pass' filter (Path: Filter>Other>High Pass). Using the sliders that come up, select a low/middle radius (such as 10, which is my go-to setting for this technique as well as the Photoshop default).
Your image has now changed again! Now it appears at it's normal contrast, but is super sharp. Invert it (using Ctrl+I), which will now (hopefully) reveal exactly what you intended the skin surfaces on your subject to look like. They're now very soft indeed, however, so is the entire image (though you'll notice that a lot of detail has been preserved, unlike if you use a similar technique but with a Blur filter).
Some fine tuning is required.
It's time to use Layer Masking so that you can fade in only the bits you do want soft (such as the cheeks and forehead, not around the eyes, hair, etc.). To begin; make sure you have the top layer selected and click on the Layer Mask Icon (arrowed).
Next, select the Paint Bucket on the left hand menu, choose black as your primary colour and set the master opacity to 100%. Click on the image, which you will then notice seemingly reverts back to it's original state (you have just temporarily rendered the last few changes invisible). Now, select the paint brush tool, and change your primary colour to white; this will enable you to later 'paint in' the effect you just saw, wherever you would like it. I'd recommend using a soft brush for this, to properly blend in what's been softened and what hasn't.
This is where I would now paint in the 'soft' effect. In my example, I have painted over the cheeks, forehead and neck (so to keep the eyes and facial features in full detail). You may wish to do more depending on how much of your subject can be seen in your image (such as back, legs, arms, etc.). On completion of this stage, my example looks like this:
You may notice that your subject, despite what you have done thus far, still shows a couple of more significant spots or blemishes. This means it's time to break out the Healing Tool. To keep it simple, I'm going to use the Spot Healing Tool (location is pictured) which fixes most imperfections with a single click. For more detailed work, please feel free to use the Healing Brush proper, but this will require additional Ctrl clicking. I recommend setting the brush to a softer setting for this also.
My almost-finished image is below; just one more thing to do now to finish off, which is to use the Sharpening brush (careful, not at too high a strength or you'll create artefacts) to really make the eyes pop. After that, congratulations, you've finished!
Before and After are below. You're now ready to further edit your image to your heart's content. Good luck!