People are interesting. One of the most common subjects in photography is people. People show up in other people’s photos more than almost any other subject. The reason for this is simple: people are interesting.
In taking a picture of a person, this is something that is important to keep in mind. It is easy to get into a habit of just pulling out your camera and snapping a picture of someone without any further thought. However, what makes that picture a “keeper” is generally how it interests the viewer, whether that’s you, the subject, or someone else. If no thought it given to what you are actually trying to capture, you leave it up to chance as to whether or not that picture will end up being a keeper.
Make it interesting. To make a photo interesting it is important to know what you are trying to capture, e.g., her laugh, his courage, her eyes, his shoulder, her wisdom, etc. It can be physical thing (a body part, an object being held, the subject in relation to the background or foreground, etc.), or a concept (an emotion, a feeling, etc.).
When you have that in mind, nothing else is as important as taking the picture and capturing that.
EVERYTHING TECHNICAL IS SECONDARY TO CAPTURING YOUR VISION.
Some people approach photography with questions such as “what camera should I buy?”, “how many megapixels do I need?”, “how do I make my pictures look like such-and-such photographer?”. While these questions are understandable, they are not the most important ones that need answering. The first step in becoming a great photographer is learning how to decide on what to capture and then doing so by whatever means necessary or available.
In portrait photography it is important to capture the unique characteristics of your subject, including their personality, attitude, emotion and features. If you succeed in doing this, you can take photos of people in the same location with the same lighting and the same settings and have each one look unique and individual.
In summary, figure out what you want to communicate with your photograph (what you want others to see when they look at the picture), and capture this by any means necessary.