My Tip: You will LOVE it!
My DW and I took our first cruise for our honeymoon in 2002. We assumed it would be a "once in a lifetime" thing (we weren't big travelers before that). Boy were we wrong! This march will make our 3rd cruise, and 6th time staying on land since then.
My Serious Tip: Do as much as you can during the 4 days on board. There is SO much to do on the ship, and even more on shore. There is so much to see and do on the ship that you will probably forget you are in the middle of the ocean!
The only regrets we have ever had during any disney stay was that we didn't do enough (we are young and don't need things like sleep (j/k)), even though we were always busy.
Anyway I don't know if any of that made sense, but have fun and maybe we'll see you on board!