By placing a naturally occurring picture element to the front and near the borders of your composition, a natural frame is created. The close proximity of this framing element to the front of the picture also increases the perceived distance between the foreground and background of the image.
The technique requires that you thoroughly investigate your subject from every angle to find framing elements that compliment your composition.
In the Rose Garden image above, the flowered archway presents a natural frame and entrance into the formal garden. Being darker than the rest of the image, the archway adds depth and provides a path for the eye to enter the picture.
This Oregon Coast line is framed by a native evergreen tree to add interest and emphasize the infinite ocean and sky seen in this picture.
The overhanging roof of a small San Francisco shop provides a natural frame that emphasizes the height of the TransAmerica tower and guides the viewer's eye to the subject.
REMEMBER: To have the framing element in focus as well as the rest of the picture, a large amount of depth of field is required (smaller aperture opening).
Use this simple framing technique to add another element of interest, professionalism and depth to your pictures. Nothing tricky here. Just a willingness to train your eye to see the framing possibilities surrounding your subjects. Like everything else in photography, it's mostly a matter of practice, practice, practice.