916. Learn the rules. Then break some.
Don Blair, who most of you never knew, but have hopefully heard of, used to tell people all the time, "You have to know the rules before you can break them!" His favorite "rules" were about lighting and posing. He respected the rules because they represented the greatest collection of tools he had to create flattering images of his subjects. The rules were all about his ability to exceed expectations...EVERY time. Remember, there was no Photoshop for Don...he couldn't liquify twenty pounds with a click on a computer, but had to rely on his skill as an artist.
Now, think about your own work. Take the time to learn lighting, posing, exposure and composition. Learn everything you can do with your skill set before post-processing. It'll not only save you time, but you'll elevate your work as an artist and be on your way to becoming habit-forming to your clients.
And...when you need to break the rules, for whatever reason, you'll have the incredible satisfaction of understanding them and elevating your work to becoming one of the great portrait artists. Every artist can break the rules, the key is to know them first!