Since the port in Galveston was closed due to fog and we did not make it to Mexico, I can only give tips that are useful while on the ship.
This is a "fun" ship which means if you like to party (drink & dance) and/or have children then this is the ship for you.
Following are some tips that might make your sail easier:
The food on deck is cold and bland. Go to the dining room and spend a few extra minutes. I was seated right away and it's worth it.
Although I consider the staff to be professional, trust no one. That's why they put a free safe in the room and yes the employees are in and out constantly to tidy up.
Play the casino the first two days (out to sea) as they are "loose" but take your chances coming back (returning to dock) and they "appear" to tighten up.
Most of my fellow passengers including me suffered from sinus problems so pack the meds if you have them. Don't assume the ship will have the medication you need.
Take advantage of the many ship-sponsored photograph opportunities. The sitting is unlimited and free with several backgrounds from which to choose. That way you get a full session and only pay for the ones you want. The pictures are ready the next day and can be viewed at your leisure with no sales pressure.
I was impressed that there was no selling of timeshares or free cruises. Thank you for that Carnival Cruise Lines!
Bring a hairdryer because they don't provide one in the room.
Bring a power strip because there is only one outlet.
Customs takes a long time. If you are leaving out of Houston, book your flight three (3) hours later so you can make it on time. Seriously.
Wait for the sales in the gift shops that happen on the return trip. Everything seems to go down in price when returning to port.
Take a watch. I saw one clock on the whole ship and you will need to know the exact time to make it to each event. Don't bother using your cell phone because you won't get reception in your room which means the time on it will be wrong.
Use the elevators next to the casino. There is no wait and it's in the middle of the ship so easy access to everywhere.
I hope this helps and wish you the best on your cruise!