Packing for a cruise is an absolute art, but there are a lot of things that really work in your benefit when you are taking a cruise. The first thing and the most important thing to consider is all the destinations that you'll be heading to. For example, if you're going on a world cruise that'll take you from sub-tropical to the Arctic or Antarctica then you'll really need to prepare.
The biggest mistake that people make is to pack with mainly their departure destination in mind. But this is of course a bad strategy. You may find that when you then are on the boat you will have way too many warm weather clothes, or not enough if you are departing from somewhere cold. If you're going to be somewhere that's quite tropical then you'll need to book a lot of bathing suits and light and thin clothing.
While the weather will be very warm and you won't need to wear much each day, you will actually sweat through everything, so you won't be able to wear each item of clothing for more than two days before it starts to smell. For advice on what to pack you should consult your cruise liner's website. They will be able to tell you everything that you need to know and will be able to provide you perhaps with a detailed run down of the sort of items that you need to take. Then, when you begin to pack and you begin to purchase items for your cruise you will be able to not miss anything out and you will be able to ensure that you do not have too much of anything.
Packing for a cruise is not very complicated, but you do have to ensure that you do not forget simple items like walking shoes if you have a shore-excursion that involves hiking or something similar regarding a shore-excursion that require special clothing that will not be provided by the people conducting the actual activity. However, cruises are on your side when it comes to packing for a cruise. Unlike packing for air travel you don't have to worry about putting liquids or sharp objects in your luggage.
And there probably isn't a limit to the amount of luggage you can take just guidelines. Those cabins are usually fairly small after all, so you'll want to avoid filling them up with luggage bags!