I think avoiding foot problems (whether it's blisters or pain) can really be helped by wearing the right shoes. I've had multiple foot problems (two heel surgeries in each foot). I used to have pretty bad foot pain at WDW, but discovered
Skechers Memory Foam sneakers for my trip in February 2014.
These shoes ROCK! They have about a thick layer of memory foam, and cushion your feet amazingly well. I had brought them, along with a couple of other pairs of shoes, planning to rotate them. I bought the Skechers about two days before my trip, and didn't have any time to "break them in" before leaving. I started wearing them the first day, and wore them all day, every say of my trip.
Never had a single bit of foot pain, and not a single blister, the entire trip!
These arre the ones I got:
http://www.skechers.com/style/11792/synergy-a-lister/nvbl