One thing I'm actively doing (and this might not apply to most people) is losing weight! I can prepare with walk, after walk, after walk, do all the stretches I want to, but I know from past experience that I just can't stand 12 hours and walk 10 miles comfortably at current weight, regardless of how much training I do or how broken-in my shoes are. So I'm doing all the walking prep and whatnot, but I'm also making sure those feet actually have fewer pounds to carry around come October.
Last trip down, I was just miserable on the last day, with feet so numb that the gf and I skipped a nice dinner at Ohana in exchange for the Contemporary snack bar, because it would require the minimum amount of walking! But the trip before that one, I had a much easier time of it, didn't get so fatigued, didn't have throbbing feet, etc, so I'm trying to get down to that weight. Dr. Scholls gel inserts and well-worn shoes also count too, and I'll try out some foot creme this time.