Not all portraits of people need to be head and shoulders or full face.
Sometimes the only way of achieving a good portrait is to photograph a person full length, and to include some of their environment.
When choosing a viewpoint for full-length portraits it is important to remember that photographing a standing person from low down will accentuate their height and make their legs look longer.
Conversely, photographing the same person from a high viewpoint, looking down on them, will foreshorten them and make their legs look shorter.
When using a wide angle lens, care must be taken if the person is placed at the side of the frame.
Some wide angle lenses, especially very wide angle ones, distort the extreme edges so that, for instance, a face will look 'stretched'.
When photographing a group of people full length, make sure that all their faces can be seen.
This is not just a case of careful positioning, but also of making sure that the shadow cast by one person does not fall across the face of another.
If the portrait is lit by flash make sure that this is spread evenly.
Many built-in flash systems do not produce a very powerful light.
A person standing in a large room may be well lit but the background will be dark and murky, because the flash was not powerful enough to light the whole room.
When photographing people full length outdoors in bright sunshine, be careful if anyone is wearing a hat.
The brim can cast a dark shadow on the face.
If necessary use fill-in flash to soften this shadow and eliminate the possibility of obscuring the facial expression.