Rust

Fabric, cloth furniture and carpet: Squeeze enough juice from a fresh lemon to thoroughly saturate the spot. Generously sprinkle on some salt and let that set 24 hours. Rinse with cool water and repeat is needed. Refresh the lemon juice several times.

Metal surfaces: Treat metal immediately. It's easier to treat a small spot than to sand and repaint. Use navel jelly from an automotive supply store.