wooo hooo, do we love to cruise. We have been on about 6 of them. Carnival, Royal Caribbean, Holland America, Norwegian. Carnival would be the least expensive, and usually has lots of kids, families with kids. We have really had a great time on all, overall best would be Royal and Norwegian. Holland and Norwegian are usually more expensive than the other 2, but shop around. We got great deals on those, actually cheaper than Royal, the times we sailed with them. I would definately use a travel agent, like the one post recommended, we always got better deals with them than I could find myself.
Book your excursions prior to boarding to insure you get the ones you want, some have limited space and sell out fast. You can't use any cash on board, you must use their equivalent of an onboard credit card, KEEP TRACK of your purchases and all receipts. Twice, we had "charges" on our account that we didn't make, they were supposedly made on-ship but we were off on an excursion (can't be in two places at once), thanks to the fact that we could prove that, they removed the charges. One good thing to know about cruising that would have helped. The last night you have to put your luggage out early (times depend on the cruise line) to be picked up. We didn't know this and didn't have any carry-on bag with us...we didn't have anything to put the clothes we were wearing, pajamas, all our toiletries, etc. the next morning. We didn't want to buy one of their "overly priced" bags so we (along with some other first timers that didn't know it either) just used garbage bags..it was funny and something we will laugh about and remember. Happy Sailing!