Bring a mug or insulated cup to carry water around and drink lots of it! The ships water if very good, no need to bring bottled water in my opinion.
One more thing, plan to stay up late late at least one night, catch the pro jam, come down to the piano bar, just wander around and see what's happening. I suggest you do it fairly early in the cruise, 'cause you may discover you want to do it again... and again. Take naps, don't drink too much, sleep when you get home, or on the flight home.
Have fun and see you soon!
Jan 2006, Oct 2007, Oct 2008, Jan 2010, Oct 2011, Jan 2012, Booked Jan 2014