In the long term there are a lot of things one can do (or can encourage their sig other to do).
Personally I first take a scrubby thing (such as a pumice) and run it over the entire foot, not just the rough spots, very very thoroughly. Then what I like to do is to soak my feet in a tub of water that's just as hot as I can stand it, and leave them there for about 20 minutes or so or until the water cools or my feet feel waterlogged. 😛
Then I pat them dry, and apply liberal amounts of a pleasantly scented mousterizing lotion, making sure to rub it inbetween the toes. Then I put them in some nice, clean, soft, 100% cotton athletic socks to keep them clean and to let the lotion do it's thing.