My family got back from a cruise this past Monday. I used cruise critic to plan that trip, and other cruises we have taken. It is a great site. Also, I like
www.cruisecompete.com for finding an agency to book my cruises through.
Consider booking your cruise throught the cruiseline direct, rather than an agency. This way you can check the prices frequently and if they have dropped since you booked, you can get the difference credited back to your credit card. We've done this every one of our cruises. Carnival credited us back with approx $800, Royal Carib credited us back with $1500 for our Liberty of the Seas cruise and a bit less than that for Freedom of the Seas cruise. (If you really want an agency, you can wait until the very end, near the travel date, and transfer your ressie to them at that time, and receive whatever perks they are offering, such as free gratuities.)
If you book thru an agency, you still qualify for the credit if you find the driop, but then the cruiselines will only deal with your
travel agent, so unless you have one avail to you 24/7, you may miss the price drop, as they sometimes only last for a few hrs. Sometimes they will accept a printout proving you saw the price drop, but not always.
It's so easy to just call the cruiseline or go online to book the trip yourself, and you may save money in the end! They say the best time to watch the prices for a drop on your cruise date is the date near the day the full payment is due, as many people book and then can't pay at the end. However, we found our price drops within the 3-4 weeks prior to our cruises - one time there were three drops for the same cruise, and that was on their brand new ship - we were on her 5th sailing (LOS)! I was going on the site twice a day to check, and it was soooo worthwhile!
Cruisecritic.com will help you navigate thru all of this, for whatever cruiseline you choose. For Royal Carib cruisers they even have a thread devoted to a Meet & Greet for each sailing. You can register, and get to know some of your fellow cruisers online, and then meet them on board during a wine & cheese party where small gifts are raffled off. We did this once, and met some really nice people. ENJOY!