>>16222211: Wear shoes tailored specifically for your feet. (cost isn't too much more and you get a far better product!)
2: Wear properly fitting socks (not 1-size fits all types.) There should not be any loose sections.
3: Keep feet dry at all times.
4: Switch socks out if any part, of the socks, starts to become loose.
5: Stop, sit down, take off your shoes & socks and rest properly. Massage your feet during this time. Check footwear and skin for problems.
6: If at any time you even think there's a tender spot forming where a blister may appear, stop, fix the problem, and rest for a while.
Enemies of your feet:
Ill-fitting shoes and/or loose shoes.
Loose sections of socks.
Remember, socks are intended to take the place of your skin. They should hold to your skin without moving against it. Any friction should be taken by the sock, not your skin. This is what helps to prevent blisters. Wet socks tend to have problems adhering properly to your skin. They tend to develop loose sections that can be easily stretched out. This is where blisters can start forming. Properly fitted shoes can radically help prevent this even if your feet are wet, but keep your feet dry anyway.
Any footwear that causes foot placement problems or has a bulge or divet where it shouldn't have will cause you all manner of problems. For instance, many people who wear steel toed boots will have their large toes go numb and/or have shooting pains in them. Over time this will become permanent. This is because the boot doesn't flex properly as they walk and the boots aren't tailored to their feet. Something as simple as a thick sock that has a thicker section of material in the wrong place on the bottom of the foot can cause bruising of the foot. For this reason as well as when they get wet, you should have several changes of socks with you.
Life can be pretty fucking harsh when you have a bruised foot, damaged toes, and/or blisters on your heels and you are 10+ miles fro your vehicle.