5. Stick close to port

In some regions, places of interest are near the port where the ship docks — think Barcelona, Venice, Naples, Stockholm, and most of the Caribbean — so you'll have more time to explore your destination. But in other areas, sites may be hours away from port via bus or taxi (Florence, Italy; Hanoi, Vietnam; and Bangkok, Thailand), which just means more time in traffic and less in the place you actually want to be.