I'm a little ashamed to admit it, but I always had a hard time remembering where the "hinge" was on the slashes.
Let me explain: Assume that the slash begins like a pipe |. If the slash has a hinge at the bottom (like most people intuitively assume), then / is "leaning forward" and \ is "leaning back". However, if, when you look at the slash, you assume the hinge is on the top, then it looks like / is "swinging back" and \ is "swinging forward".
So until I figured out where people were putting the "hinge", "back" and "forward" seemed arbitrary. I know it sounds strange, but it was a great source of confusion for me.
Edit: The phrase "lefty loosey, righty tighty" also confused me until I figured out that "left" and "right" were relative to the direction that the top of the screw/bolt moved, not the bottom.