Make sure to have good lighting while you are making portraiture. The light can be natural (ambient) light or artificial light. It all depends on how you want the end product to look.
The background can change the mood of the photo, so make sure to have it right.
A white background is a good start, or you can create your own background pattern by adding shadows that fall on the background. Another option is to let the shadows be a foreground pattern that fall on the model.
Take sequence shots to show the personality of the model.
This will make the eyes stand out. Also, focusing on the nearest eye will keep the "out of focus area" behind the point of focus.
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