Always clean your boots after use," says Dave Page, owner-manager of Dave Page, Cobbler in Seattle, a major repair and warranty center for large retailers and manufacturers. "Take them to a utility sink and scrub them with an old veggie brush. They usually come home wet, so water's fine. Remove the footbeds. Dry the boots at normal room temperature, with no heat. Put a waterproofing treatment or a leather conditioner on them if they look dry. With modern, cemented-sole boots, don't overwaterproof them, and don't use any, I mean any, heat, because it can cause the sole edges to delaminate."
"Boots are pretty maintenance-free and durable," says Rick Applesies of Vasque. "But when you get a boot saturated and muddy, the mud draws a lot of moisture out of the leather as it dries. So after cleaning and drying, use a silicone-based leather treatment to recondition the leather. Silicones are absorbed better than wax treatments and don't tend to clog pores or inhibit leather breathability as much. Things like mink oil will soften leather too much. When boot leathers are tanned, often times stiffeners are put into the leather, and you don't want to lose all the support."
"Never put your boots next to a fire or stove," cautions Dave Smith of Danner Shoe Manufacturing Co. "Two things can happen. Put 'em too close, and you singe or melt or burn the materials. Second, wet leathers will shrink as they dry, and the boot's fit will change. Finally, don't wear your boots when working with pesticides, herbicides, and any other chemicals, since they can cause a sole to peel.