When I photograph, I use no rules and let my perceptions govern the final image. Here is a great description of how that works:
DANCING WITH SQUARENESS
“Photographs are boxlike. We have a square camera with a square perspective. That squareness seems to be our general frame of reference. But we don’t have to be too concerned with that squareness—we could dance with it. Let’s view that corner, this corner, this corner and that corner. Above we could allow lots of space; at the bottom we could allow a lot of solidity; on the sides we could play with how we view our world. If the world is pushing us to the left or the right, we could go along with that. As long as we don’t fight there’s no problem. We could have the right invading our left; that’s okay, that’s a nice picture. If the left is invading our right, that also makes a nice picture.”
Chogyam Trungpa, “New Sight” in True Perception: The Path of Dharma Art.