Place painter's tape on both sides of the glass around the wrought iron.
Lay a drop cloth on the ground around the door to prevent any paint, paint chips or rust from getting on the ground and contaminating it.
Scrape away any paint that is chipping with a putty knife.
Scrape away rust spots on the wrought iron with a stiff wire brush. Take care while doing this so you don't scratch or break the glass in the door.
Sand the surface of the wrought iron lightly with a medium-grit sanding block or sandpaper. This will scuff the surface and make it easier for the paint to adhere to the wrought iron.
Wipe the dust and bits of rust off the wrought iron with a tacking cloth.
Brush an exterior-grade rustproofer onto spots where the wrought iron is rusty or there is no paint covering the metal. Allow the rustproofer to dry.
Paint the wrought iron with a paint that is designed for use on metal and contains a rust inhibitor. This will help prevent rust from occurring, and will also adhere to the wrought iron better than a paint that isn't designed for metal. Apply the paint with smooth strokes, and make multiple passes over the metal with the brush to prevent the paint from dripping. Allow the paint to dry.
Pull the tape off the windows.