Hey! I went on a 7-day cruise last spring break when I was 15, and wrote a day-by-day review of what I did everyday, as well as what was going on onboard the ship and in the ports! I think it might be really helpful!
Teen's Review of NCL Dawn cruise 3/24-3/31 - Cruise Critic Message Board Forums
I can give you packing tips, advice, the whole nine yards if you want, just let me know!