First Time Cruiser

Hi!
Doing my first Disney Cruise, (well, actually, it's my first cruise ever) in less than 5 weeks. Just wondering if you have any advice?
I can plan a trip to WDW with no problems but I feel completely out of my element with this cruise. I've booked excursions and did my pre-check in.
What types of clothes should I pack? Do I need anything really dressy?
I am in check-in group timed for 12:00-12:30. How much earlier than that window can I arrive?
Any on board activities that I shouldn't miss?

Help!

What ship are you sailing on? And how long?

For the Dream/Fantasy- you definitely want to try the AquaDuck! It is a lot of fun. The shows on board are amazing (I've been on the Dream and love all 3 shows. And will be sailing on the Fantasy in 2 weeks and can't wait to see the 3 shows there). The Midship Detective Agency is a fun game for both adults and kids (and the Fantasy has a Muppets version). For dining- you will want to look decent for dinner (you don't have to do black-tie if you don't want to, not even for the Formal night on 7-night cruises. But you really don't want to go to dinner in jeans). Bingo is a fun event onboard. And there are all sorts of events as well. Finally- Castaway Cay. The Pelican Plunge slides are fun!

Unfortunately I can't answer on Magic/Wonder (but they look great too).

And you can arrive earlier then that window

Four day on the Dream.
Excited!!!

The Dream is a beautiful ship! I'm sailing again next Sept, and looking forward to it. You'll have a great time :)

Remember that if you're going to dine at Palo or Remy there is a dress code that is a little higher. I think it's a jacket for men at Palo at least. As far as activities on board that you shouldn't miss, I'd say be sure to see the fireworks at sea.

You can arrive at the port as early as 10:30, I think. However, I don't know how much earlier they might let you in if your arrive early. Last cruise that I was on they had a different procedure.

Just relax, though. You'll find it to be an easy and fun experience!