After thinking about it some I realize that I do a bit more. I guess I do take the sand traps, contour of the green, and drainage into account as well. I have been doing it so long that it's just second nature to have a feel for the break and visualize a line. I will add one other thing. You should be properly fit for a putter. I have learned that everybody sees straight a little different. I was fit for an Edel putter. During the fitting I lined up with my old putter and was completely blown away by the difference in my perception vs what was actually straight. It has made a difference in my game. I recommend them to everyone.