Cut the aluminum foil into small squares. 3" by 3" should do.
Wipe down or wash the surface to remove any surface dirt.
Dip a square into some water or sprinkle some water on it and spread it around on the surface of the foil.
Cup the wet square over the surface you want to clean so you get a nice even coverage.
Start rubbing a 6 or 8 inch area and remember you don't have to rub very hard. As you rub, you'll feel the surface get smoother and smoother until the foil just glides over it. You will also notice a
light brown paste building up. This is the polish that results from the chemical reaction.
When the surface is nice and smooth and you have polished it, take a clean cloth and wipe the polish off.
Once you finish cleaning and polishing the item you need to cover the surface to protect it from the elements. At a minimum you can wipe it down thoroughly with a clean cloth. Since cloth inherently
contains some amount of oil, this will give you at least some protection.
The best method would be to use a small amount of chrome polish or maybe something like turtle wax or an equivalent kind of wax or polish. Make sure you wipe the surface down with a paper towel first instead of a
cloth because paper doesn't contain any oil so you will have a clean and dry surface for the wax or polish to adhere to.