J O H N  A L L A N wrote:
This is mostly lighting skill.

And understanding how to control exposure along with light ratios for effect (which I know you understand, btw.).

I often see folks here discuss exposure as if it's an objective matter.  While it is when it comes to testing, it is very subjective when it comes to image making.  Sadly, many who haven't shot film, never studied (even at a cursory level) the zone system, used a light meter or printed traditionally, don't really understand this. 

In this case the photographer has decided where they want the skin tones to land within the exposure curve and has balanced the lighting in the scene to match that vision.  The same lighting setup, with the skin exposed a stop brighter would yield a dramatically different result. 

The good part of digital is this is very easily experimented with.  Create a simple setup (you can do this as self-portraiture for the exercise) and take a meter reading, either incident or spot of a grey card.  Yes, even though your camera has a meter for this kind of stuff, you really would benefit from owning a hand-held meter.  If you don't, use a grey card and spot meter it with your camera.  You want to establish a base, "correct" exposure with the grey card in Zone V.  If you do this, assuming the lighting the scene is consistent, your skin, especially if you're caucasian, will most likely register at Zone VI.  If you're super pale or have super dark skin, there will be variation.  That's fine.  Take that shot.  Now stop down so that your grey card reads Zone I  (close down four stops) and take a photo.  Open up a stop and take another photo, rinse and repeat for ten stops.  Bring all those photos into your editing software of choice and white balance them all to the same point.  Look at the skin, the tone, luminosity, texture, etc.  Decide on what you like best.  If you're going for a stylized look, first experiment on the correct exposure, then try applying it tall the photos you took, figure out what the right balance between exposure and color grading is for the look you want.  Now, once you have that, experiment with tighter lighting setups, more contrast, less contrast, etc. all the while making sure the skin renders at the same point on the curve that you tested for.

This will get you much further than playing in photoshop (which is fantastic, but that's a follow on step).