Mix a drop of dish washing soap in a bucket of water. Dip a clean rag into the mixture and wipe down the wrought iron. Clean nooks and crannies with a brush or even a toothbrush. Add a few drops of turpentine to a steel wool pad if there is a great deal of dirt and rust on the wrought iron. Scrub the wrought iron with the steel wool pad.
Add a heavy grit sand paper made for metal finishes to your electric sander. Sand all the rust and old paint off the wrought iron. Continue sanding until you remove all of the old paint and any rust spots you see. Change to a medium grit sand paper to get a smooth sanding finish.
Mix a drop of dish washing soap in a bucket of water. Dip a clean lint free cloth in the soapy water and begin to wipe off the sanding dust and other debris from the wrought iron. Continue to dip and wipe the wrought iron as necessary until it is thoroughly clean.
Apply tape to any areas you do not want to paint with primer. Set the wrought iron in a well ventilated area and on a layer of newspaper so you don't paint anything you shouldn't. Put on a painters mask to avoid breathing in paint fumes.
Spray a rust resistant primer on the wrought iron. You can find this type of primer at any home improvements or hardware store. Allow the primer to dry for a couple of hours and apply a second coat if necessary.
Spray on an enamel paint color you want for the wrought iron. Use a paint that is made specifically for metals. Use a paint compressor or spray paint. Spray on a thin layer of paint and allow to dry for an hour or two. Apply a second coat if necessary.
Spray on an acrylic topcoat to protect the iron. Allow to dry overnight and apply a second coat. Your wrought iron is ready to display.