CROCS! These work the best for me. They are on sale right now on the website; enter "crocs25" on the checkout page for a 25% discount. Two pairs, with tax and shipping, came to $52.
ROTATE your shoes, even if they are the same style of shoe. It makes a difference.
SPRAY your feet every morning with an aerosol antiperspirant. Let it dry before putting on your shoes. This helps keep my feet from sweating in my crocs (without socks, of course!).
MOLESKIN- stick this on "hot spots" before your feet blister. Put this on drained blisters (sometimes I put a piece of gauze over the actual blister itself before covering the area with moleskin, so the stickum doesn't stick to the soft blister skin).
MASKING TAPE- This is the secret of the Rockettes, which my DD learned when she went to their training course. Put it right on your skin anyplace your shoes rub. Keeps blisters at bay! DD swears by it!
I think you'll get as many answers as there are posters, but this works well for me. YMMV.