Here are some things I have begun in my campaign for 'goddess toes'--
Soak them in the tub and then use a foot brush-pumice stone on them, with plenty of antibacterial liquid soap.
Always grease them with petroleum jelly before putting on socks. A new coat before new socks. Believe it or not this has crumbled away quite a bit of callus, depriving fungus of places to live.
Paint the nails with polish once trimmed to correct dimensions despite hating to lie around until it's dry. My soccer-playing man said it actually inhibits the fungus, and even though Riven disagrees, he wears it himself so I believe him... though it does tend to flake off fast if the nail is fungus-y. My man's toenails don't flake because they are healthy. For a bit I actually used flesh color and painted the entire ends of my toes, just to be proactive.
The feet are responding positively, though they have a way to go yet.