just normal spray paint from your local car spares shop. Rub them down with some sandpaper only fine stuff you dont have to take all the paint off. Highbuild primer helps the paint to stick better and fills out little bumps in the steel for a better finish. Then just mist your paint on to prevent runs.
Its best if you allow about 20mins between primer and paint. And a minimum of 30mins (if in a warm area, longer if not) to allow the paint to harden before re-assembly