Never let rules get in the way of what you can move around in Photoshop? Difficult question. I should look through some of my "beginning photo" books to see what the rules are. I try not to divide the frame horizontally or vertically right in the middle. But with portraiture (or trees or flowers) I relax this. Almost never shoot with the sun behind my shoulder. Overexpose negative materials, underexpose slides; [meter the shadows with negatives, meter the highlights with slides]. Generally dislike bright sunny "vacation" days, prefer overcast, fog, rain; except for crisp bright winter snow.