The most common mistake made by photographers is that they are not physically close enough to their subjects. In some cases this means that the center of interest—the subject—is just a speck, too small to have any impact. Even when it is big enough to be decipherable, it usually carries little meaning. Viewers can sense when a subject is small because it was supposed to be and when it's small because the photographer was too shy to get close.
Don't be shy. If you approach people in the right way, they'll usually be happy to have their picture made. It's up to you to break the ice and get them to cooperate. Joke around with them. Tell them why you want to make the picture. Practice with people you know so that you are comfortable; people can sense when you aren't
Settings—The Other Subject
The settings in which you make pictures of people are important because they add to the viewer's understanding of your subject. The room in which a person lives or works, their house, the city street they walk, the place in which they seek relaxation—whatever it is, the setting provides information about people and tells us something about their lives. Seek balance between subject and environment. Include enough of the setting to aid your image, but not so much that the subject is lost in it.