I have tried a number of things and this is what I have found works about the best, short of going to a shoemaker and having them do the job. ( that can be pricey).
Take a toothbrush and with baking soda, clean the scuff to get all the dirt out making sure that the surface is clean and dry after. the take white shoe polish and work it into the scuff with a clean tootbrush. (Using a toothbrush is the best as it doesn't do further damage to the surface) Let that dry and then put a light coat of mink oil on the spot and let soak in overnight. Coat again with mink oil the next day, at least 24 hrs. later, and lightly buff with a soft cloth. This seems like a lot of work, but it hasn't failed me yet.