Mix baking soda and vinegar or baking soda and lemon juice into a paste and rub on and then wipe off with a clean wet dish cloth.
Vinegar, Water, Dish Detergent and Baking Powder as a slight abrasive per need.
I use Dollar Tree Awesome Orange in hot water. I also get the large car sponge and kitchen rubber gloves for the job. I buy it in the half gallon for all my clients, but they also have it in a spray bottle.
I use Krud Kutter from Home Depot. It is safe and it works great. I even use t to remove grease before painting furniture.