The best advice I can give is to not sweet the small stuff. Go expecting to have a great cruise, you'll have a great cruise.
The Dawn is one of NCL's best, so you made a great choice.
1) Don't forget your papers. Have a passport, or driver's license and birth certificate handy when embarking.
2) Pack lightly. The Dawn has self service laundrymats, so you really don't need to pack for 7 days and nights of clothes.
3) You have to get reservations for the specialty restaurants, but not for the main restaurants. The food is served in small portions, so either order every course, or you can order two entrees if you wish.
4) You don't have to go ashore at every port. The ship is far less crowded on port days, you almost have the entire ship for yourself.
5) There will be chair hogs, line breakers, constant complainers, loud and drunk passengers aboard. Expect your fellow passengers will often be rude. Let them be, just walk away from them.
6) Expect the crew to try to sell you more things. They know they have a captive audience. Remember, you don't have to buy anything you don't want.
7) Last, and most important, have fun!