Here's something that I've noticed that I hope someone could explain to me.
My approach is that I put a line on my ball, line that up with my aimpoint and when I'm over the ball I focus primarily on lining the little line on my club up with the line on the ball.
I've noticed that when I'm on a steep slope (say 4% at 90*), with the ball below my feet, and stand over my ball, the line does not appear to be pointing to the same place as when I lined it up from behind the ball. It always looks like its lined up with MUCH less break. If I putt along the line on my ball, i miss low.
It must be some sort of perception/optical illusion sort of thing caused by the slope. Like I'm not looking directly down on the ball or something? Is this some basic problem that every hacker cures their third trip out or am I some sort of weirdo? Hopefully something in between?