I've been told by experienced hikers that there are two kinds of blisters, or better said, two ways to get blisters, from pressure and from friction. On my first Camino, I had horrible blisters, and with bigger boots on the next Camino, I did much better. To avoid the so-called friction blisters, I put Sportslick ointment on my feet every morning and wear a liner sock under a smartwool sock. I change the liners once during the day. And one last thing. I don't know whether it helps or not, but we have found that taking our boots and socks off for at least a half hour mid-day rest keeps our feet feeling much MUCH better. On the first Camino, we never took our boots off during the day, thinking that we would never be able to get them back on. Nothing could be farther from the truth -- taking them off and airing (or even soaking in cold water) the feet does wonders. They feel much better. I don't know if that contributed to the lack of blisters or not, but my feet felt much better.