Recently, my Dad stayed with me and we did some woodworking. He's very much a Norm Abrams type and I'm more handtool oriented. He brought a LV dovetail saw, and a couple planes that he said never "worked" right. It was while showing him how to start the saw without it grabbing and ripping wood that I realized the single most important thing I do with hand tools. I look at my reflection. More specifically, the reflection of my workpiece in the shiny part of the chisels and saws I use. I rely heavily on lining up the layout marks in my saws reflection so that the lines are straight and level. I do it also in the reflection of my mortise chisel as I chop a mortise.
Do do you guys do this as well?