If you are doing any type of portrait work, you are already aware how vital it is to have great skin tones on your final shots for the client. There are a lot of different ways to accomplish this. The first and foremost process for having great skin tones in portrait photography is the lighting. Without good lighting you will not be able to capture the smoothness or textures of a clients skin. If you light your subject correctly you assure yourself much less hassle in postproduction editing in Photoshop.
Depending on the look you're going for, I always use some form of soft box for lighting skin tones in portraits. Getting a soft box on medium power three or four feet from your target area on your subject is a great placement for a nice soft light that will bath the skin just ever so slightly. Typically I place a soft box at a 45 degree angle to the subject, but that doesn't mean you shouldn't move it around and experiment with different placements. A great way to get a really soft lighting setup is to bounce a soft box off another reflector. This in essence gives you a double soft box and diffuses the lighting greatly.
While searching through YouTube for skin tone lighting ideas and techniques I came across this tutorial video which has some great tips and techniques for skin tones in portrait photography.