Lighting and shooting a good portrait is only half the work; after you have taken the winning shot, you still have to edit the image, which is where the other half of the magic happens. This excellent video tutorial will give you a comprehensive lesson on retouching a portrait using Photoshop.
Coming to you from Eli Infante, this helpful video tutorial will show you how to retouch a portrait in Photoshop. In the video, Infante runs through a range of techniques and features, including frequency separation, dodging and burning, layer masks, selective color, levels, blend if, and color grading. It is important to have a firm grasp of all these techniques, as they all contribute to a complete image, and a deficiency in any of them is often easily noticeable. Personally, I think one that often gets a bit overlooked by beginners is color grading. We focus so much on blemish removal and retouching that we sometimes forget to add a more personal artistic touch like color grading, but this can be a huge part of developing a personal style; just be careful not to go overboard with it! Check out the video above for the full rundown from Infante.
And if you really want to dive into shooting and editing portraiture, check out "Fashion and Editorial Portrait Photography: Lighting, Retouching, and Shooting for Magazines With Clay Cook!"