So much has been written about blisters! I've read about hardening your feet, alcohol rubs, creams, the best socks, change your boots, Vaseline and a lot more. I don't now believe a word of it! I've had blisters, really bad ones but they are well in my past now.
The best advice I had was to buy womens boots (narrower ankles) and since I started to do this, for me no more blisters! Its not really that simple however, the tingles and signs that a blister could start can be always there so I have developed my own routine for MY feet. Every time I stop I take my socks off and turn them inside out, I massage my feet, (heaven!) and then rub them with a wet flannel and just let them dry. When I'm ready to go again I put my socks back on, inside out and off I go to the next stop.
As regards hardening the feet, sorry I don't subscribe to this idea! I have soft flexible skin and I'm sure that because, as I walk my skin 'gives' so I am less inclined to blisters. If I had hard skin I feel confident that it would encourage blisters, not stop them. Other people I'm sure have different views on this but I am now happy to walk day after day without blister discomfort.
I do get sore feet, underneath mainly, I put that down to the effect of walking long distance, the type of terrain travelled over, rocky or not and the weight of the rucksack on my back.
Of course footwear and fit is most important as well. Ive just walked 12 days along mainly rocky landscapes. I'd bought a pair of Brasher Superlites a couple of months before and they behaved fantastically! So comfortable (even on the rocky footpaths) and not a twinge of a blister at all, in feel or in sight! Sore bottoms of my feet though, carrying a rucksack for so long, twisting around on rocks for day after day does take its toll but definitely no blisters!