Always go to a reputable travel agent. If your state has a requirement for licensing as a Seller of Travel, select a travel agency that is licensed. Many Home-based Agents don't follow this legal requirement, but here in California it's a felony!
My agency is a member of two consortiums that have group space on several different cruise lines and itineraries, so that is very important for you the client because it gives better options and sometimes pricing.
Some agencies offer "perks" for booking with them as well, which you won't get from other agencies or the cruise lines themselves. You also need to find someone who can give you first hand advise - it's not the wisest to buy a cruise from someone who hasn't cruised in 10 years.... their information would be quite out of date.
For more information you can contact me via MSN or Email, or check out my Cruise website www.ShipVacations.com.
Always glad to help a fellow traveler -