I. Pack For Your Cruise Destination
The basic fundamental for cruise packing is to pack for your cruise destination's expected temperature and weather. Pack what you are going to need for the destination that you will be going to. For a warm weathered cruise wear lighter clothing and for a cold weathered cruise wear warm clothing. For example on a Caribbean/Bahamas cruise you will probably want to consider bringing clothing like short sleeved shirts, shorts, bathing suits, and light clothing. For an Alaskan cruise you might want to consider long sleeved shirts, jackets, mittens, ear-muffs, and warmer clothing. Make sure you pack clothing that will keep you as comfortable as possible in the destination you are going to.
II. Don't Leave Home With A 100% Filled Suitcase
Leave some room in your suitcase before your cruise. This will allow you some extra room to bring home anything you buy on your cruise ship and in ports of call. If you buy too much and do not have room to pack it back into your suitcase for your return trip, you will have to hand carry your items off the cruise ship. Also, if you do not leave with a fully packed suitcase your baggage will be slightly lighter when you are trying to check your luggage in to be brought onboard the cruise ship. This is always a benefit for you and those that will have to carry your luggage!
III. Renting Formal Wear Onboard (If Possible) Vs. Bring Your Own
Most cruise lines and ships have 1-2 formal nights on each cruise vacation. Many ships have a "Formalities" shop where guests can rent a formal outfit for the cruise, based on availability. However, you can also bring your own formal wear onboard the ship. Bringing your own formal wear onboard the ship means that you could save some money and would not have to worry about messing up ship's property. A benefit of using the formalities shop onboard would be that you would not be obligated to buy formal wear before you leave and you would avoid taking up space in your suitcase. If you are bringing your own formal clothes make sure you keep your clothing nice and know what is acceptable for formal dress onboard your cruise ship.
IV. Create A Packing List
I recommend a week prior to leaving on your cruise vacation, you form a packing list of things you are going to want to pack for your cruise. A packing list can help keep you organized. If you choose to create a packing list, you can cross items off your list as you pack them for the cruise. This will help you avoid forgetting essential things that you meant to pack.