Pick a warm, dry day to paint your wrought iron pieces. Don’t start painting if surfaces are wet, when the humidity is more than 80 percent, if the temperature is less than 50 degrees or if the piece you're painting is directly in the sun.
If you’re painting movable wrought iron pieces, choose an open area outdoors, covered with drop cloths or tarps for your workspace — you don’t want overspray or splatters and drips to ruin surfaces that you don’t want painted. For fences or railings, make sure that the ground and surrounding surfaces are protected by drop cloths and painter’s tape so they aren't marred by the paint if the overspray is caught by the wind or if the paint drips.
Set up a large piece of cardboard, lightweight wood, or hang a drop cloth or sheet as a shield against overspray that might blow onto other objects. Place the "shield" on the side opposite of the one that you're painting.