Pack for varying weather, even if you are going somewhere warm. You will spend periods out on open water, which could bring wind and possible rain, so it is a good idea to pack a light jacket. If your destination will be cold, there may extremely sunny days when heavy winter clothes may make you hot in the sun.
Weigh your luggage. There may be weight and size limits on your cruise ship. Cruise lines are not as strict as airlines, but they do have some weight and size regulations. Check on your cruise line's website to see luggage restrictions. Use a hand scale to weigh your luggage if you are unsure.
Pack plenty of essential toiletries and medications. You can buy replacements for easy-to-find-items, like soap and sunscreen, during your land excursions.
Place the items you will need for the first day in a small carry-on bag. You will not want to wait for your luggage to be delivered to your cabin to go swimming or have fun. First-day items include your bathing suit, camera, laptop computer and sunscreen.
Pack in twos. Bring at least two bathing suits if you are going somewhere warm, and pack at least two heavy sweaters if you are going somewhere cold. Think about the item you will be using most and bring two. Many cruise ships provide laundry service, so you will be able to alternate.
