SOME CRUISE LINE LINKS:
TIP - if you own at least 100 shares of Carnival stock or Royal Caribbean stock you can get a shipboard credit based on the number of sailing days. That's for any of the cruise lines in that family. For example Carnival owns Holland America, Princess, Costa, Cunard, Seaborn, Aida, and P&O. I bought Carnival stock many years ago and not only has the stock increased in value, we've gotten over $1200 in shipboard credits.
TRAVEL AGENTS: There are thousands of cruise travel agents. Here is just one that we have used and have had good experiences with. Again, this is only my opinion.
UNITED CRUISES - We use them lately to get additional United Airlines miles for cruising. American Airlines also has one if you save their points but we haven't tried them yet.
CRUISE PLANNERS - Nancy Bogert, good to work with and has great deals.
SquareMouth - Weird name but a great place for comparing policy prices on many companies
OTHER INTERESTING SITES:
US State Department - Travel Information