We look up to people we admire and we look down on people we despise. This rhetorical convention provides us with a visual point of reference when it comes to our compositions.
The lower we place our cameras, the more heroic our subjects will appear. As we raise our elevation we lower the visual strength of our models. Slightly elevating our lens above eye level will start to give the viewer a sense of dominance as they gaze down on the face of our model. By increasing the height of our perspective even more, the subject starts to appear weak, then meek.
So if you want to give your subjects power, stay low. Think of using this perspective for an executive or someone we want to revere.
If you want your subject to be supplicant, stay high and empower your viewer.
Inversely, the broader the subject appears in your frame, the more dominant they will be. Whereas a person turned to the side and appearing to be more narrow, will be less intimidating to the viewer.
And One last thing to consider are gender stereotypes. This will guide most photographers’ decisions, but there is nothing wrong with shooting women low and men high.