Moleskin is amazing and great but in my experience don't get a cheap, no-name brand. I've had experiences with the sticky part not working all that great and the moleskin moving and bunching up and then causing it's own blister.
Moleskin was a godsend for me especially after a blister had formed. I haven't had to use moleskins, though, for at least 3 or 4 WDW trips. Instead I switched to Teva pretty rugged sandals, rather then sneakers and socks, AND most importantly, I started using Bodyglide (and Blistershield which does the same thing) for the hot spots. It works like the deoderant another poster mentioned but it's specifically made to prevent blisters and chafing. I also use it to prevent chafing on my inner thighs and thankfully, I haven't had anymore chafing either.