Stay hydrated, drink plenty of water! Cruise food is so rich and delectable, you'll want to stay "regular". My first cruise I overindulged in eating, especially all the foods that were heavily sauced and cheese filled without staying adequately hydrated. I enjoyed my cruise, but I wasn't able to move my bowels for a while.
I do wonder about this, even when I stay at hotels. It's the reason why I always travel with a can of Lysol on every trip. I spray down everything when we get to our room.
I don't mind an inside cabin, but a balcony is my preferred room. I like that RCL has an option of an interior room with a promenade view! They're the only cruise line that I've traveled with that offers this option, which I think is cool.
Unpopular opinion, I've mostly flown in the day of my cruises. I'm not opposed to flying in the day before and have a couple of times but majority of the time it's been the day of.