Deck, interior, engineering, galley. Whether you have four seasons behind you or none yet — register either way. We would rather know you exist before you are certified than after you have already found something.
It takes about three minutes.
Registration is free and always will be. Under MLC 2006, crew are never charged for job placement — the vessel pays, not you. If any agency asks you for money to find you a job, that is not how this industry works.