When I was a kid my father would tell me every time before heading afield - you can ask me to stop 10 times a day to ‘prevent’ blisters and I won’t get mad. We’ll put on dry socks, a dab of Vaseline, moleskin or dust tape and tighten your boots. But ask me to stop ONCE to TREAT a blister that has already happened, and you’re in trouble mister!
I’ve lived by that - prevention prevention prevention. I know that is not helpful advice for you now that you have them. So in that regard, the company “Band Aid” makes these gel thingies that you stick over the existing blister and it’s surprisingly helpful. They are very tapered down to the edges so it doesn’t ‘roll up’ when you resume movement. But they hurt to take off. Another option are the Dr Scholls ‘corn rings’ - they are made of adhesive moleskin an make a ring around the blister and hold your sock up off it. I have made similar custom ‘rings’ out of moleskin to build up around the blister. Advantage is when you take them off you’re not tearing blistered skin.
In terms of prevention, I’m a big fan of liner socks as mentioned by others, something slippery like silk or polypro. I know the Cabela’s and wigwam socks mentioned above as well, and will add to that a sock called Wright Sock, which is a similar double sock with a the liner sewn in. Huge fan of those. Changing socks more often helps a lot as well. And yet, boot fit of course. Last trick that I use when hunting pheasants dawn to dusk is to change boots at lunchtime. They’re dry and have different pressure and rubbing points.
Cheers,
Dave