On Disney, there are booking windows that open. 75 and 30 days from date of sailing; know when yours is. 12am EST. Know what you want to book, excursions, tastings, etc. There are lots of helpful posts on this topic on this forum. 30 days out is also check in day. You'll need to have certain information at hand to complete check in and select a port arrival time. No big deal if you get a later time. I find the earlier you're there, the more crowds and waiting around you'll see.
Something else, DCL specific, is that people like to participate in fish extenders and decorate their doors, but this is too completely optional.
As others mentioned, besides the cruise fare, budget for gratuities, excursions, and any other activities in port.
Booking a room. There's pros and cons to all.
Inside: costs less and many still offer a split bath. You can select a room pretty much anywhere on the ship. Some people may want to be near the MDR or kids club, or not near the theater or under Cabana's. It's nice to have no window and to sleep in in the mornings; or if you have a napper, the ability to go dark in the afternoon. Downside, no natural light, no private outdoor space.
Oceanview: Great rooms, too. Natural light but no balcony. Mostly what I don't like about these is that they tend to be on the lowest decks. Some people love the location though.
Verandah: Can be pricey, especially on DCL. I love getting up in the morning with a cup of coffee, or sitting out there with a glass of wine. Anytime we've booked one, I've been lucky to spot marine life somewhere along the way. Great rooms, but I'd rather save my $ and book a second cruise if I can. If you have nappers, you can be nearby while still enjoying being on a cruise ship (I don't like to sit idly in the stateroom). Some people feel they are must haves, but there's plenty of outdoor lounging space on the ship.
Concierge: Haven't done it. But there's perks, like priority embarkation, bookings, etc.
mode.
