Post-production is core to most genres of photography, though it is more important to some than others. Portraiture is one of the most intricate areas of retouching with tricky tasks like skin retouching. Watch as one photographer talks you through his entire portrait editing workflow.
Portraiture is undoubtedly one of the most popular genres of photography and for good reasons: people like looking at people. When I started out, I read a study (which may or may not have been legitimate, but it still sounds reasonable enough to me) that claimed photographs of people, on average, held viewers for the longest amount of time.
As I became more and more obsessed with portraiture, I noticed some gaps between my work and the work I wanted to create that other artists were. This has always been my method of improving at anything and I doubt I am alone; if somebody is doing something better than me and I like it, I need to work out how to bridge the gap. There were a few ways I improved my portraiture, with posing and lighting be two primary routes, but a third was post-production. I didn't ever want to create unrealistic-looking glamor-style portraits, but I did want to edit my images to be more in line with commercial work.
If you're looking to improve your post-production work for your images, one of the best ways to achieve this is to watch a talented photographer edit their image and talk you through it, which is exactly what Eli Infante does in this video.