You'll get lots of recommendations on which agency has the best deals--but since no agency always has the best deals on anything, it's best to shop around.
You can either go web-site to web-site, or use a service like www.CruiseCompete.com
that lets you select a cruise then get multiple competing price quotes.
If you're concerned about not getting the cabin you want, you can reserve through the line and cancel or transfer the booking to an agency later if you find something better. Do check the policies on cancellation fees--usually if you're at least 90 days out there are no fees.
Dawn Princess 12/14/03