If you can, thin socks and either really thick or thin socks over them. Heel rub happens when the sock sticks to your heel (sweat) and also to the inside of the heel counter on the shoe. Two layers this does not happen as the layers slide past each other. I always liked Blundies when they were made in Taswegia, but they've fallen off the radar now.

Wear thick socks because they can start to hurt when they're new.

Thirding the thick socks. My Steel Blues were absolute bitches to break in, but once I did they became my favourite shoe ever.

Seconding the thick socks!! It's the heel rub that gets me. Get Dubbin if you don't already have any.