A trick I have used for years to prevent blisters is to place a piece of adhesive tape over an area where I'm prone to get a blister. I place a piece on my right heel, and wrap another piece around the 4th toe of my left foot. Ever since I started using the tape (before a blister starts), I've been blister free. I believe the principal behind this is that the sock will move smoothly over the tape, instead of rubbing the skin directly. Just my $.02.