Fill the Frame
Filling the frame refers to making your subject take up a major portion of the frame, or image. It's very easy, particularly if you have a basic point and shoot camera, to shoot photos like the following picture from a Civil War reenactment in McKinney, Texas.
There is nothing really compelling about this picture. The soldiers, trees, foreground and background, all get about the same visual treatment, when the soldiers are really the only interesting part of the image. Here is another shot of the same group that is much better.
What's the difference? In the second shot, it is zoomed in on the group and filled the frame (the entire area of the photo) with the subjects. The background is slightly blurred because of the zoom, and the subjects are accentuated. The subjects are interesting and they dominate the image. That is the strength of filling the frame.