You'll have a great time. My first tip would be to read through this forum. Many of the same tips and tidbits of cruising knowledge get discuss over and over again in this forum. So, read through some of the other message on cruise questions and most of your preliminary questions will get answered quickly. If you can't find an answer or have a different question, come on back and ask it and you will get more help than you probably wanted.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013