Blisters are caused by abrasion against the skin. Lubricating the skin can keep that abrasion from causing blisters. The lubricant you use should be one that will last for the length of your walk. Apply any lubricant liberally to your feet in any area that is prone to blistering.
It's cheap and it works. I put great gobs of petroleum jelly on my feet before I put on my Cool-Max socks. No blisters, not even on a marathon - and I used to get big heel blisters every time at 10 miles. No, my feet don't slide around in my shoes - the socks prevent that. No, it doesn't feel slimy once you put on your socks. It doesn't wash out well but who cares - these are walking socks! Use the plain petroleum jelly, not any of the fancy cream versions.
A no-petroleum stick that goes on like a deodorant stick. It won't stain your clothing. It comes in regular and a version that includes sunscreen. It's good for preventing blisters on your feet. I use this by itself for 6-10 miles walks and put it on first, before the petroleum jelly, for longer distances.
2Toms produces two kinds of silicone-based blister prevention lubricants. One is a SportShield, a silicone-based roll-on or towelette that provides long lasting lubrication to prevent blisters and chafing. It is odorless and non-greasy. The second variety is BlisterShield powdered silicone to put into your socks to help prevent blisters.
Think of it as high-tech petroleum jelly. It combines silicone, polymers, and petroleum jelly for long-lasting waterproof lubrication. It includes aloe, antioxidant vitamins E and C and natural plant extracts, To fight athlete's foot, it has tolnaftate antifungal agent and it has Triclosan antibacterial agent to prevent bacteria and odors.
Squeaky Cheeks is a cornstarch and essential oils solution for those who don't want to mess with greasy preparations. Sprinkle it in your socks to help keep your feet dry as it absorbs sweat. The oils also help lubricate and reduce friction.
Engo pads don't go on your feet, they go into your shoe in the spots where you have developed blisters or hot spots in the past. Their slick surface reduces friction in these problem areas. They stay in place up to four weeks. An advantage of Engo is that it won't gum up your socks, and you can use it with cornstarch or other drying agents.
This formulation of BodyGlide is labeled specifically to stop foot blisters and chafing. Oddly enough, it has a strong perfume scent. As I am allergic to most added scents, this was not a plus for me. Luckily, if I put it on my feet it won't reach my nose. But I prefer the orginal unscented formulation as I can use it both on my feet and my underarms and other places to prevent chafing. FootGlide, like other BodyGlide products, is made with plant-based waxes. It has no petroleum, lanolin, or oils.