* The subject: A portrait format is generally good for focusing attention on a single subject, especially when you want to emphasize their height, face, or upper body. However, a landscape format might be better if you want to include more of the subject's surroundings or show them in a wider context.
* The environment: If the background is important to the story of the portrait, a landscape format can help to showcase it. This is particularly true for environmental portraits where the setting plays a significant role in understanding the subject.
* The story you want to tell: A portrait format can create a sense of intimacy and closeness with the subject. A landscape format can suggest a sense of space, grandeur, or distance.
* The intended use: Consider where the portrait will be displayed. A website banner might be better suited to a landscape format, while a print for a wall might work well in portrait format.
* Compositional elements: Consider how you want to use compositional techniques like leading lines, symmetry, or the rule of thirds. A particular composition might work better in one format than the other.
Ultimately, the choice between portrait and landscape format is a creative decision. Experiment with both and see which one best captures the essence of your subject and tells the story you want to tell.