1) Two opposites schols of thought: harden or soften your feet before leaving.
I used to harden with Tano or lemon juice, starting about 3 weeks bc (before Camino). Did great, no blisters. But this year I could not be bothered and only got a tiny blister on top of the thumb joint. Perhaps my feet are not prone to them, or there is something else I do that makes thedifference?
2) Vaseline, Bagbalm,Dimethacone, Vick's Vapour Rub every morning before leaving. All worked equally well, or again my feet are not prone to blisters. Could not be bothered this year and all I got was that little thimbtoe blister.
3) Socks. Liners are a pain in the behind as they tend to slide down and bunch up on the bottom of your feet. Regular shapped socks in Merino or other wool did well by me. Only regular shape socks that do not work well for me are Wright's as they keep my feet moist. And there are Injinjis. One would think that the toe socks may be annoying but no, super comfy. BUT... The medium thickness with cause the skin at the base where the toe meets the foot decomposes and tears after 2 days of wear. The "lights" I was able to wear for 10 days or so before the same thing occurs. This also happensto me when diving 4 times a day, day after day, starting after 5 days or so.
4) After walk treatment. The only thing I still swear by, as I have not tried to walk without it yet that is. And what I use is Saint-John's Wart Oil. Recommend to me by the owners of the hiking store in Astorga 4 years ago. Also by avid mou tain walkers met on the Norte 2 years ago who used it to help heal 2inch wide blisters, skin off!, on the ball of the foot of an unfortuante walker who had walked in the rain as it is also an antiseptic. A couple of drops on each foot after your shower and go. Super light to carry and does tripple duty: antichaving for the day, antisceptic, and sking softener.
5) A trick I never tried but same mounteneering guys on the Norte recommended to man with blisters is femine hygene pads on between sock and foot to absorb moisture. Again, 2 schools of thought: stick side up, or down ;0).
Now, I think the consensus is that the second you think you are getting a blister, or better yet hot spot, stop and slap something on it: tape, bandaid, compeed.
Good luck!