Oftentimes the reservation you are given already has your exact stateroom picked out. But if no stateroom is assigned, make sure you write down the type of stateroom you booked. That way you know exactly what you should be getting when you check-in.
If available, check to see if your
cruise line has an app that will make the check-in process easier. This will save you a lot of time when it comes to boarding the ship. Yes, you'll still have to go through security and check your over-sized luggage, but the process of actually checking-in to the ship will be lessened.
Be sure to double-check when the online check-in process needs to be completed by-most cruise lines won't let you check-in with the app within 24 hours of departure.