When I finally pulled the trigger on my first camera, I took out a bunch of photography books from the library while I waited for it to ship. The rules of composition came up over and over again: the rule of thirds, diagonals, leading lines, golden ratio...

I don't think I ever internalized them much. I really tried for a bit, but these days I mostly just shoot by feel. Diagonals do seem to keep popping up in my shots, though.