One of the best ways to improve your portrait session is to start with a plan for posing. My uncle Knolan Benfield had a studio in Hickory, NC, where he did mainly portraits for his business.
You may have seen some of these folios that many photographers still sell as a way to display more photos from a session for the client.
He realized he could shoot to help sell those and up his average sale. Well, it worked. He started to pre-visualize the photos in the folio.
The customers were buying more photos, and he was getting better pictures for the customer in the process.
At first, it will feel a little mechanical and formulaic, but you start expanding the poses over time.
At first, you may just be having a person face to one side and then the other. Slowly, however, you will start to experiment. You begin to learn that each basic pose of the body is endless when you start going for different expressions.
What surprised me was the likes on the fun photos versus just stunning photos of theatre students I did this past weekend.
Summary
Shoot to for a folio
Add a photo each time you do a portrait
Try for different expressions in each pose