Depending on your environment, you could backup all your core files (given you haven’t hacked them) and the DB. It’s also a good idea to backup your beta. Next, switch over – if it’s production to live for client / public, do it during a time that traffic is lowest, assuming you track your traffic.
Release the beta site at the domain (depending on your environment you might need to sterilize the DB and change URL paths) – if it fails, revert using your backup. If all goes well, the transition should be without issue upon upgrade.