Remove all paint and rust using either sandpaper or a chemical remover. Both items are available at hardware and home improvement stores. For severely rusted wrought iron, a chemical remover is best. When you are finished, you want to be able to see the silver iron underneath.
Wash the wrought-iron furniture thoroughly to remove any excess paint, rust or sandpaper debris. Allow the furniture to dry completely.
Spray or paint on a rust-resistant primer that is made especially for metal surfaces. Again, these primers are available at hardware and home improvement stores. This will protect your furniture from future rust.
Paint the wrought-iron furniture with paint made especially for metal surfaces. Do not use house paint, as it will peel very easily on metal surfaces.