Hi Patricia. I'm Cindy. To clean bronze, put a tablespoon of baking soda into a small dish and squeeze some fresh lemon juice into it, making a paste. Use a small piece of soft cloth to rub this paste onto your bronze pieces. Then wash the mixture off under running water. Next, dry and buff with a clean soft cloth.
This looks like a good article for directions to clean bronze. Good luck! https://www.hunker.com/13420709/how-to-clean-and-polish-bronze
Patricia, for home made supplies, we use baking soda and lemon juice (if I don't have fresh I have used the bottled juice) and rub a paste on the bronze. Rinse and wipe clean/dry with a soft cloth. Hope this helps. When all else fails, We have just simply spray painted oil bronze over the exterior to make it look new again. This we did on some decor and bed frame that was bronze. I would not recommend spraying antiques, objects that are decor and costly, but for daily use objects it greatly improved the look and was the fastest, easy way to bring it back to life.