To make a homemade cleaning solution for unlacquered brass, dissolve 1 teaspoon salt in 1/2 cup vinegar and stir in enough flour to make a paste. Ketchup and straight lemon juice are also effective brass cleaners.
To clean brass that is not lacquered, squirt a small amount of ketchup onto a rag, rub it over the brass, wipe off any residue with a damp cloth, and buff the surface dry. Lemon juice also works to bring back brass' shine - clean the surface with straight lemon juice, wipe with a damp cloth and buff dry. You can also use a mixture of salt, vinegar and flour, rub it into the brass and let it sit for 10 minutes, then rinse and buff dry.
Commercial and household cleaners damage lacquered brass. To clean lacquered brass, simply wipe it down with a soft, damp cloth.