The method I used is actually quite simple and the only supplies you need is vinegar, water, a clean towel, a shoe brush, and some shoe creme.
Combine the water and vinegar, and mix them well. I used about 50% water and 50% vinegar. Dip the towel into the water and vinegar mix, and wipe the towel gently over the surface of your shoe. The leather will noticeably darken as it absorbs this new liquid, but don’t worry about that, just focus on the ridge of salt that sits on the shoe like dirt. You want to keep rubbing the solution onto this ridge until the leather is smooth again. Continue this process until the stains have fully disappeared. Then let the shoes dry for about an hour, but do not place them near a heater because artificial heat could damage the leather.