I will throw my prop accident story in the mix too. When I first started I had a 20 size trainer. I started the plane from the front and a little to the left of the engine, and as I was getting up to go around behind the plane I bumped the wing with my knee. This caused the plane to yaw right. the running engine hit my elbow and the prop made four cuts before the engine quit. I swole up about an inch above normal and bled like crazy. I should have gotten stitches but I didn't, I still have the scars to remind me to be careful.