1) Travel using a passport, not just a Birth Certificate and Driver's License. The first plan was to tow the Carnival Triumph to Progresso, Mexico for repairs and disembark all the passengers there. They would then be put on flights home. Over 900 guests on this sailing of the Carnival Triumph did not have passports. Since passports are required for arrival in the U.S. by air, it is not clear how those folks would have gotten home. I'm sure that the U.S. Government would have done something to help in this extreme case, but those that had passports had one less thing to worry about. If you don't yet have a passport, what are you waiting for?
2) Bring extra clothing, medicines, and anything else you can't live without that will last at least several days beyond your planned end of vacation. If you are taking medicine that must be taken every day, this is very important. If you are on a land vacation, and you get stuck somewhere, you can call your doctor and have them send a temporary prescription to a nearby pharmacy. I did this when my wife and I were stuck in Orlando for 3 days trying to get home from a cruise during Hurricane Sandy. If you are stuck on a ship floating in the Gulf of Mexico, you are out of luck unless you have enough with you. You can bet that I'll take at least a 10-day supply with me on my next 7-day cruise.
3) Pay attention at the muster drills. Fortunately the fire on the Carnival Triumph was contained to the engine room and was extinguished and the ship was in no danger of sinking. However, if that fire had spread, and it was necessary to evacuate the ship, would everyone have known where to go? When there is an emergency situation that is not the time to be trying to figure out what to do. Advance planning could save your life.
4) This incident and a few others that have happened in the last several years is no reason to stop taking cruises. Just count up how many successful cruises have been sailed during that same time period, and you'll see that cruising is one of the safest modes of vacation travel. Individual incidents make headlines due to so many people being involved. The same is true of airplane incidents. In either case, you are safer on that vacation trip than you are commuting back and forth to work each day.
So, plan ahead and be prepared. Then you can relax while you are on vacation, knowing that you can handle anything that comes your way. Now call your travel agent and book that next vacation.