The rule of thirds is one of the most powerful creative options you have when composing your photograph. A photo that has the important element of the photo at an intersecting point of a “tic tac toe” board, or in one of the right or left, top or bottom thirds of the photo, is one that is more compelling than a shot with the subject centered.
Most often, you don’t want to position your subject smack dab in the center of the frame. It’s boring. Although, this rule, like all rules, can be broken very effectively. That really depends on the shot. But if you start to think about not putting you subject in the center of the frame, you will train your eye to see better shots. For example, the eye closest to the camera should hit one of the intersecting points. Or the critical part of the landscape should be in the top third or bottom third, left third or right third. My shot here shows the subject off to the right slightly and in the lower portion of the frame. This gives the subject breathing room in the frame, the “white space” (which does not have to be white, but rather unimportant or non-distracting space in the frame) gives your eye a place to rest and then come back to the subject, and by positioning the subject as I did, you get a feeling of where she is and that where she is important to me and therefore should be to the viewer as well. Below is another example. This time a vertical landscape that also adheres to the rule of thirds. I added the tic tac toe board to both images also so that you can get a better idea of where the intersecting points or thirds of a frame are.