Determine how much you can pay for your cruise. You need to realize that the amount you pay for just the cruise is probably the lowest dollar item of your vacation. Nearly everything except food and entertainment is an extra charge. This includes drinks and offshore excursions. Cruise lines, like everything else, vary in price from economical, such as Carnival, to extravagantly expensive, like Celebrity or Crystal. There is a comfortable price for everyone who wants to cruise.
Choose a cruise line that appeals to you in regard to the type of people you want to spend your vacation around. Some cruise lines are known to be family-friendly, such as Disney Cruise Line, as opposed to a cruise line that caters mostly to the retired, well-heeled crowd. Crystal Cruises is an example of a little older demographic.
Decide where you want to travel on your cruise vacation. The itineraries of cruise lines differ. Some cruise lines--Carnival, for example--sail fairly close to the United States with ports of call in Mexico, Jamaica, Puerto Rico and other fairly close island stops. For a very different cruise experience, consider taking a trans-Atlantic cruise on the QE2. This is expensive, but it is a once-in-a-lifetime opportunity.
Consider the size of ship you want to sail on. Some cruise lines--Royal Caribbean, for one--keep building larger and more outstanding ships. There are several Royal Caribbean ships that actually have a pool that you can surf in. These ships are huge and hold up to 4,000 passengers. Each cruise line typically has different-size ships in its lineup. You can usually have your choice of a smaller, more intimate ship if you are taking a river cruise through Europe.