What are yours to share?
My top three are -
1. Arrive at the Port at the designated time. Getting there too early causes a log jam type situation with those Debarking the previous cruise with parking etc.
2. Have your documentation in hand and ready to show at the first security check point. This would be your Fun/Boarding Pass, ID, and proof of citizenship ie Passport - Birth Certificate.
3. Bring an Ink Pen to fill out the Health Declaration and Credit Card Authorization in the terminal for check-in. If not you will be using one that everyone else has touched.