Things I Learned From Cruising Last Week

• On vacation, people don't pay the slightest attention to anything around them, including you. I guess they've decided to turn off their brains for the duration. Best to pretend you are a bicyclist on a busy urban road surrounded by semi-trucks (which is really not that far from the situation). Cruise lines can be very crowded and you need to put on your PolitenessMan (or Woman) hat from the moment you leave your house.
• If you're expecting to get drunk, you're going to need to do it onshore or be pretty determined on the boat. 
• Don't touch anything and wash your hands often. We live in a world where antibiotics are overused and no longer work in some situations, and people are slobs on vacation. 
• People are very friendly, but don't bring up another country's politics unless there's only one person present from said country. I got asked by a British couple if I thought Obama would be re-elected and what I thought was a pretty neutral answer (US is extremely polarized right now and the result largely depended upon what last minute problems or revelations or accusations came out) was met with another guy telling me that he hoped I had a nice day even if I was a Democrat (I'm not). 
• If you're counting your pennies when it comes to additional charges, you are taking the wrong trip. Figure that your passage is about 50% of what you'll spend, depending upon how many excursions you go on and how much you drink. 
• The people who aren't officers that you'll interact with are getting about $5 a day (or close enough for government work) and will go for months without seeing their families. Whatever the company suggests to tip them is between 50-20% of what you should tip them. Tip generously on board the ship. Also, be very nice to them. They work in conditions that are illegal in the US and even an offhand comment or joke can have a negative effect on them. Above all, avoid being patronizing or snide to them, and avoid jokes about their culture or where they come from. Get to know their names and greet them when you see them. Service on a cruise ship when you have a family back home is a very hard job with few if any benefits. 
• Cruises have become marketing opportunities for captive audiences. You will be besieged with "special offers" to buy all sorts of things, from fake diamonds to duty free booze. The chances are extremely good that this is no deal at all. 
• Unless you have a good reason not to, take the stairs. 
• Unless you have a good reason not to, avoid the buffet and stick with the dining room. 
• You will need a bigger suitcase because you will go through a *lot* of clothing. At least one extra change of clothes per day. 
• You cannot overdress. You can definitely underdress.
• Just because you won't see anyone you know does not mean that you can dress like you did 20 or 30 or even 40 years ago. If you are over 30, and possibly over 10, I really don't need to see the tattoos on your midriff. 
• If you can barely squeeze through your stateroom door, probably best to cut it down to three meals a day. 
• Sometimes the entertainment is good. Sometimes not. If you aren't sure, sit near the back. 
• If you don't want to swim, a deck chair on the Promenade is a better bet. 
• Don't assume anything that runs on batteries will still be charged when you get on board. My blood pressure meter, freshly charged when we left and with me not bringing a basic USB cable to recharge if necessary (and no laptop to charge it with) was useless after one use. 
• Old people are going to complain. A lot. About everything. Especially trivia answers. 
• The winetasting can actually work out pretty well. We had an excellent sommelier on board and some excellent canapes to go with the wine. 
• Did I mention washing your hands often and avoiding touching handrails unless you have to? Especially true before meals. I even stopped biting my fingernails for the week. 
• If you are prone to seasickness, acupressure bracelets are great and have no side effects. Research anything else carefully - we were warned off of patches, but other people have had good results with them. Treat it like any other medication you would take. 
• Once it's time to leave the boat, you are just another piece of luggage to be loaded off onto the dock. Get over it. 
• Book your cruise through an experienced travel agent. Every boat and every cruise is different and you'll want to get on the one that doesn't have all Central Europeans hogging the deck chairs and chain smoking. 
• Always choose to sit with people you don't know, then get to know them. Even if they tell you to have a nice day even if you're a Democrat. 
• Everyone will have a line they prefer, and a line they won't go on it you give them a free ride. I have had good experiences on Regent and Princess, less good experiences on Holland and Royal Caribbean. Apparently no one likes Norwegian, but I've never been on that line.
• If the cruise offers lectures on the area you're cruising in, attend at least one. I learned a lot about the Mexican-American War, as well as the Spanish colonization of the Americas, and even got in the Mexican Armada Museum in Puerto Vallarta. Better than gambling. 

This was my fourth cruise, and (barring my first experience on a very small boat that is no longer in service) my best experience with the sole exception of the music, which was awful except for the production band which also made up a jazz trio that was excellent. The food was good (away from the buffet), the ship was clean, there were no breakouts of the plague (and that happens, more than you'd think), and the staff was excellent. BTW, we did a seven day cruise down the Mexican Riviera (Cabo, Puerto Vallarta) on the Sapphire Princess. 

YMMV.