Consider throwing away the brush or towel after using it to avoid spreading mold spores. A great tool to use for scrubbing is an old toothbrush. You can dispose of it when you’re done. Check the storage area for mold and mildew as well. Many times, the spores grow in warm or damp storage areas. Dilute bleach in water to neutralize the spores.
Make sure the cloth or brush isn’t dripping wet. Leather isn’t meant to be soaked in water. A light coating doesn’t harm it and also helps the cleaner you use next.
Lye is harsh on leather shoes, so avoid cleaners with heavy amounts of lye. Instead, make your own or get a product specifically designed for shoes. Any leather treatment product you need, including soap, is available online. Also, check at your nearest general, home improvement store, or any place that specializes in leather goods. Another option is to buy a leather maintenance kit. A good kit contains almost everything you need, including a cleaner, conditioner, filler, and applicators.
Another option is to leave the cleaner to dry overnight. This is safe to do with saddle soap, but check the manufacturer’s recommendations for other products. If your shoes are still dirty or you plan on working on them right away, dry them off by hand instead.
Consider also stuffing the shoes when you’re not using them, particularly if you put them in storage.
Heating the leather slightly, such as with a space heater or hair dryer, helps it absorb the oil. Cleaning leather with soap dries it out, so take the time to rehydrate both shoes now. Focus on the cracks, but don’t neglect other areas. Mink oil is a good match for leather, but some people find that bottled moisturizers last longer and offer more protection. These products are often made with beeswax and other natural oils. Purchase moisturizer online, at a general store, or at a clothing store that carries leather products.
Keep in mind that you can’t exactly “fix” leather. Cracks are permanent because the fibers in leather pull apart. The best you can do is fill noticeable cracks to hide them.
Consult the manufacturer’s instructions on the product you use for the recommended drying time. At the very least, wait for the filler material to solidify before adding more of it.
Use only fine-grit sandpaper. Using anything coarser can add new scratches to your shoes.
Creams work very well on repaired cracks, but you can also use them to color the rest of the leather.
Check the shoes again to see how they look. With proper treatment, the cracks will no longer be visible. Use more filler, cream, or other products as needed.
As an animal material, leather needs regular oiling to prevent it from drying out and cracking. Regular conditioning also masks old cracks and prevents them from reappearing.
