Fill the frame
People shots vary from close up head-shots to full-length. Whatever you choose, fill the frame with your subject, don't leave lots of space around them unless it adds information. A garden may be interesting if you're taking a portrait of a gardener, but otherwise concentrate on the subject and keep the picture uncluttered. This applies to all subjects, including still life, not just people.
When taking a photograph, you are there, experiencing the surroundings. That memory will remain with you. But for the person who sees only the finished picture, it's difficult to judge scale. A towering cliff, a high waterfall or vast beach, for example, have no dimension unless seen against something of a recognizable size, such as a person or building. These elements add impact.
Depth adds a three-dimensional feel to a flat picture. For example,
branches of a tree in the foreground, a building in the middle ground
and mountains in the background assist the eye by drawing it from one
element to the next. A wide angle lens can extend this perspective,
whilst a long focal-length can compress it.