www.vacationstogo.com has one of the best search engines for finding the cruise you want -- enter approx. date, departure port, ports you'd like to visit etc. Really good.

After you've found the cruise you want, check for the best prices by putting the info into www.cruisecompete.com Let agents make their best offers for pricing and amenities (OBC and/or trip insurance etc.) Double check any agent you might want to book with -- BBB, Tripadvisor, CLIA etc. The same as any other business, there are a number of "black sheep" out there, and several went "belly up" last year, reopening shortly thereafter under a different name.

Put yourself on the mailing list for www.crucon.com They run fantastic specials very often.