If you want a chrome looking finish, I suggest Alclad II or **** Stix chrome model paints. Just be aware that it requires airbrushing over a smooth black enamel undercoat for the best finish. Here's a pic of some plastic spoons painted with each. I can personally vouch for Alclad II but have yet to try **** Stix.

Edit: That's S-P-A-Z Stix.