Here's a very simple recipe for making a natural shoe polish. It does a great job, is non-toxic, and costs just pennies.
Start with a quarter cup (2 fluid ounces) of extra virgin olive oil. Add about 5 drops of lemon juice. Apply to leather surfaces with a soft rag, then buff clean. You might want to test a small amount in an inconspicuous place before doing the entire shoe.
This natural polish removes dirt and leaves a nice shine. It's perishable, though, so discard any unused polish or store in the refrigerator for up to a week.