We are going through the same thing right now....I am just doing as much research as I can.
Get a few travel books, visit the hotels website, read other brides/travelers reviews (I love doing this).
Once you have it narrowed down to a few, email each one and ask for quotes. You could even go to a travel agent, and get them to help you.
Do you have a certain date/time of day you are hoping for? DO you want a resort that is large, with many pools, restaurants, bars etc or would you prefer a smaller more intimate hotel. This site is amazing for information, and everyone is so helpful so I'm sure if you have questions/concerns they could be answered here. Good luck planning!! :-)