Don't like paying $4 for water at the airport? Bring your own empty water bottle and a powdered drink packet. Fill up at the H2O fountain. You'll be sippin' sweet tea for pennies. Plus the water cups on the cruise are tiny.
Always be sure what time the ship is leaving and if local time is different than ship time.
If you know you'll be bringing back liquids - bring wine skins with you. They are cheaper in bulk and offer great protection.
Take a copy of your passport and keep it opposite your passport. Left your passport in your room or cruise cabin safe? Carry the copy with you. Carrying your passport in your purse? Keep the copy in your pocket.
If you are trying to carry on - check out my packing list for carrying on.