Blisters are not uncommon but we were either very prepared or lucky. We did not get blisters. I wore hiking boots, 1/2 size larger than my walking shoes. And, most of the time two pairs of socks. I washed by liner socks daily and most days my other pair. When I felt irritation, I taped that area of my foot. Having said all this, it was not hot or very wet. Perhaps in different conditions, we would have required different approaches.
Most of the time we stayed at the Albergues (hostels). We wanted to support the municipal ones but the private ones seem to be operated better. They were slightly more expensive since municipals were around $5 and privates around $10. I think part of the experience is staying in the Albergues and I would recommend it. Having said that, the privacy of your own place is really appreciated when you treat yourself.
I was happy that we selected this time of year with enough but fewer Perigrinos (pilgrims). With Easter so late, there were not as many Perigrinos. So, the Albergues were at a low capacity. However, many were still closed so in a couple of cases our days lengthened since we could not find a place to stay. I preferred this problem to what I heard happens in the high season when beds fill up quickly and Albergues are very crowded. In the few cases where our Albergue was crowded, it was OK but I got relief the next day.
It is a safe, fun healthy trip. Be prepared to eat a lot and still lose weight. Since we rarely repeat vacations, we likely would not do the Frances again. We might do the Portugese starting in Porto since we have been told that finding accommodations before Porto can be difficult.