Why should you trust me about the rub? Well, I once ran the equivalent of 67 marathons in 67 days with a 25-pound backpack. Here is my toolkit for those who are trying to avoid pain.
Lubrication: Anti-scratch products such as lubricants or specialized conditioners are the best anti-scratch measures for you. Even if your carefully chosen fabric fails you, a generous coating of lubrication can help. You can't be embarrassed. Especially downstairs. You want to make sure you get to places you rarely even go to.
Go seamless: I choose shorts, leggings, base layer shorts, t-shirts, and running underwear that are seamless or have flat-lock seams. I always check the seams of pre-made double shorts, and I rarely trust pre-made inner shorts in regular shorts. If in doubt, add your own trusty underwear.
Tighten: I choose tight layers that hug my body rather than loose outfits. It may sound counterintuitive, but fabrics that stay in place and hug the skin will work better than fabrics that are loose and move around a lot.
Avoid cotton: Cotton is very heavy and can be abrasive even when dry. When it gets wet with salty sweat, it's a disaster for your tender feet. Layers that come into contact with your skin should be made from synthetic or wool fabrics. These dry faster and reduce friction.
Powder your toes: Blisters are essentially abrasions to the nucleus and are more difficult to avoid. Applying powder to your feet and socks can help reduce moisture that increases the risk of rubbing and creating hot spots.