Image by Martin Gommell
I have been using the "Rule of Thirds" for decades--ever since I took photography lessons as a college student. What, you may ask, is the "Rule of Thirds"? Explained simply on the PhotographyMad website, "The rule of thirds involves mentally dividing up your image using two horizontal lines and two vertical lines. You then position the important elements in your scene along those lines, or at the points where they meet."
There is a lot of research on this, but the bottom line (ha!, pun intended) is that the "thirds" distribution of shapes is believed by many to be the most pleasing to the human eye.
Anne Blair Brown recently wrote an interesting post for the Oil Painters of America blog, talking about the Rule of Thirds. She gave an illustration(above) using one of her