Wrought iron is a versatile material that has been used in numerous construction applications throughout the years. In fact, France's Eiffel Tower was built using a type of wrought iron. More commonly, though, wrought iron has been largely used to create ornate railings, fences and even decorative furniture. As long as it's indoors, you needn't worry too much about wrought iron rusting. Regular cleaning will suffice. Wrought iron left outdoors, however, will likely rust at some point and will require proper care.
Use your fine-grit sandpaper (120-160 grit) to begin stripping away the rust and/or paint on your wrought iron. Be sure to sand the entire area, removing all layers of paint and corrosion (See Ref. 2). You will want to sand all the way down to the metal in order to ensure you've removed any and all signs of rust. Any rust that's accidentally left behind will eventually spread and find its way to the surface once again. If necessary, use 80-grit sandpaper to remove heavy layers of rust.
Rub the wrought iron with some steel wool after you've finished sanding. The steel wool will essentially buff the iron, removing any small bits of paint or rust. When you're finished, you should be left with wrought iron that has regained its original appearance.
Apply rust inhibitor to the wrought iron. You can purchase a spray can of rust inhibitor at any hardware store. The rust inhibitor will basically act as a primer for your paint and seal the iron against moisture. This is important, as exposure to moisture is the main cause of corrosion.
Paint the wrought iron with the enamel paint of your choice. Apply at least one coat over the entire surface of the wrought iron. Once again, this will provide the necessary barrier against moisture and rust.
Purchase some naval jelly in order to treat extremely rusted wrought iron. Follow the directions on the container for the proper use of naval jelly. Use protective gloves and apply the jelly in a well-ventilated area. After the jelly has had time to work on the rust, wash it away with running water. Naval jelly contains phosphoric acid, which essentially burns away the layers of rust. You can apply naval jelly as many times as needed in order to remove all of the rust.