This blog post by Stephanie Evergreen of Evergreen Data illustrates how to take the classic photography compositional 'rule of thirds' and apply it to the creation of visually powerful slides. Included in this resource is a downloadable template for ease of use in your own power point presentations.
"There are a couple of different ways to use the Rule of Thirds. Some people will let it guide where to put images, such that the images consume one, two, or all three of the thirds, either horizontally or vertically. Other people will work to put key elements at those star points where the horizontal and vertical lines intersect.
The idea is that placement along a third makes everything off-center, which creates visual interest. Centered content (text or images) tends to feel really balanced and formal (by that I mean really boring)."