The most important rule is don't put pewter or brass items in a dishwasher!
One of the characteristics of pewter which makes it a popular material is the fact that with minimum care it will keep its original finish. It should be hand washed in warm water, or with a mild detergent if required, and dried with a soft cloth. Items with brass trim may also be washed in the same way.
Pewter items should never be washed in a dishwasher as dishwashers usually use very hot water and harsh detergents. Pewter is a very soft metal, and putting it in hot water may damage it.
Depending on the type of finish there are slightly different ways in which your pieces can be maintained.
Polished pewter tends to be very smooth and shiny, and only needs polished every few years. An all purpose metal polish will keep it looking bright, which can be found in most DIY hardware stores. Choose a gentle product which is suitable for both pewter and brass. However, if you’re feeling adventurous you can make your own using a few simple ingredients (see below).
Satin Pewter has a grainy finish. The cleaning process is the same as polished pewter but for polishing the surface it only needs a light buffing with some very fine steel wool (grade #0000). You should rub in the direction of the grain. This should only be done every couple of years or less as doing it too often will damage the surface. You should never use steel wool on brass trim as this will leave scratch marks on it.
Oxidized Pewter has a dark, antique finish and should only be washed with mild soapy water.
Make Your Own Pewter Polish
A cup of vinegar
Half a cup of flour
A teaspoon of salt
Combine the ingredients and rub in gentle circular motions with a soft cloth then leave to dry. Remove the dried paste and rinse it in warm soapy water. Dry carefully and thoroughly with a soft cloth.