THe one thing I wish I'd known on my first cruise was You can't do it all on one cruise, granted we had extra things going on that first cruise.
Take time to relax and enjoy yourself
Don't say you want nothing for dessert- you may just get it

You can order Mickey bars from rm service or as your dessert or breakfast.
You will not be allowed in Room until 1p ish first day of cruise so just remember you have to carry/lug anything you bring on with you for that time.
If you want to swim first off pack swim suit in carry on
There are 2 places to eat sit down lunch or you can grab something up on deck that first day.
Dressing up for pirate night is loads of fun- even if it's just a t shirt
You can get any picture without border just ask them to reprint it.
If you see something you like in store on boat buy it than, it maybe gone later ( I learned this first hand)
There are formal and semi formal nights on boat- I've seen everything from dockers to tuxes on those nights. ( Dh is wearing Tux on formal night and Suit on semi formal night, I have bridesmaid dresses for both nights)