Boot Care
Good boots are like puppies: treat them well when they're young, and they won't bite you when they're old.
The first priority is keeping your boots clean. Dirt left clinging to boots will work its way into the leather, fabric, seams and stitching, then grind away until the boots fall apart. Consider it a moral imperative, akin to washing behind your ears, to clean your boots with water and a stiff scrub brush after a muddy trip; a little mild soap will help.
Next, dry your boots slowly, well away from any heat source. Leather is just the skin of another mammal. Don't put your boots any closer to a heat source than your own hand can comfortably tolerate. To speed drying, unlace the boots completely and remove the insoles (and liners if you've got pac boots).
Cowhide, like your skin, was naturally oily when it clothed the cow. Also like your skin, cowhide can dry out, become brittle and crack if soaked repeatedly in water or exposed continually to hot, dry conditions. Some manufacturers now claim that their leather has been waterproofed for the life of the boot and needs no additional treatment. In my experience, however, even the best leather boots eventually begin to leak. To preserve the leather's suppleness and waterproofness, I periodically apply some kind of leather conditioner. Here controversy reigns, with each manufacturer of conditioner finding some reason to claim that rival products will rot the leather, degrade the stitching and delaminate the soles as well as give you night sweats and premature baldness. The safest course is to use the conditioner recommended by the boot manufacturer (if the manufacturer recommends one), if for no other reason than to preserve your rights under the warranty. Mink oil and neat's-foot oil are intended to soften leather which has become hard and brittle; they should not be used as waterproofing agents.
Unlike puppies, boots that won't be used for a long time should be stored in a cool, dry, dark place.