Hi!
First of all, be sure to order your free Walt Disney World planning DVD. You can request it
here. I also recommend picking up a copy of the book "The Complete Walt Disney World" by Julie and Mike Neal. It's a great book for first time visitors with just the right amount of information without being overwhelming. It's also a beautiful book full of fabulous photos. It will quickly give you a feel for what there is to do at Walt Disney World.
Also, be sure to make Advanced Dining Reservations (ADRs) as soon as possible. ADRs can be made online
here. Walt Disney World has some great places to dine! Reservations can be made up to 180 days in advance and some really popular places fill up very quickly!
I also recommend staying at a Walt Disney World Resort hotel. If your budget allows, it's hard to beat one of the Magic Kingdom monorail resorts. My personal favorite monorail resort is the Polynesian. It's fantastic!
Hopefully this will help you get started in planning. Write back if you have any more questions!