Small holes. Clean metal thoroughly with steel wool. Cover hole with plastic steel.
Large holes. For a semi-permanent repair, clean metal thoroughly. Cut a patch out of similar metal. Coat bottom of patch with plastic steel and press into place.
Seams parted. Call in a roofing contractor.
Rusted. Scrape off as much rust as possible. Prime with Rust-Oleum 769 Damp-Proof Red Primer. Then paint (see Basic Methods:
How to Paint).