I've been on 108 cruises. Here are 11 mistakes passengers should avoid making.

• I've been on 108 cruises, so I know which common mistakes passengers should avoid making.
• Sunburns and hangovers can make your vacation less enjoyable.

As someone who's been on 108 cruises, I consider myself an experienced cruiser.

Almost all of my voyages have been with my wife of 63 years, Donna, but I now face the future without her guidance and companionship.

Over the years, we've put together some thoughts to share with future travelers. Finally, I've compiled the pieces of advice we thought were standouts, particularly about what not to do while cruising.

Don't get sunburned on your first clear day at sea

If you're from Chicago and it's February, you'll likely head for the lido deck and the pool the minute you see the sun.

While relaxing on the deck for hours and drinking in the warmth, you may simultaneously be destroying your next few days with a sunburn. Be sure to protect yourself from the sun.

You shouldn't be barefoot in the public bathrooms

Generally, it's best not to go barefoot outside your cabin unless you're on the lido deck. There are too many floor hazards that you can avoid by just wearing sandals or flip-flops.

The public restrooms are no different.

Cruise bathrooms are regularly maintained and usually spotless, but that doesn't make the floor resistant to bacteria or germs, so wear your footies.

Though it may seem so, your balcony probably isn't that private

Thanks to their ingenious design, many ships' cabin layouts can make private balconies visible from the desk above or curved halls, even though this might not be noticeable to you.

Even if you have a secluded balcony safely tucked away from prying eyes, sound carries. The noises you create will be heard by others, or vice versa.

So watch the content of your conversations and be discreet in your behavior.

It's not worth trying to disguise liquor and sneak it on board

It can be embarrassing if security spots something on the X-ray scan, then takes your suitcase apart looking for that bottle or other container that violates the ship's policies.

In the process, other passengers may be treated to views of your undergarments and other personal items.

Most ships allow passengers to bring a bottle of Champagne or wine, so I'd recommend settling for that.

Don't miss your cruise by forgetting the ship's time in port

Make sure you know when you are due back on board. In many ports, the local time will differ from the ship's time by an hour or so, which leads to frantic races to the gangway for some.

We've watched a number of passengers trying to get on at the last minute, and sometimes failing.

Our most entertaining departure story involved a small navy vessel docked opposite us in St. Croix. When the time to reboard crept closer, young sailors in various stages of intoxication came staggering toward the ship, some even held upright by their shipmates.

Down the pier, a sailor pushed a wheelbarrow loaded with his shipmate to their boat as it was leaving, hoping to get back in time. They weren't even close.

You'll likely regret trying to outdrink your beverage package

I think we all tend to test the limits of anything free. And even though beverage packages definitely aren't, once paid for, temptation rules.

That said, a hangover at sea is no fun.

Although drinks aren't typically unlimited, they may feel like it based on the consumption capacity of the average passenger, and often cocktail hour can be the coup de grâce.

Don't enter the belly-flop contest, especially if you have the beverage package

This event typically entails sunburned and liquefied people launching themselves in the air spread-eagle, only for every inch of their flesh to crash down into the unyielding pool.

The beverage package may have convinced you to engage in some rather unique activities — last night's karaoke, for example — but belly flopping should be a spectator sport only. Participants usually suffer during their performance.

Make sure to get your passport out of the bank-safe deposit box — or don't keep it there at all

As a banker in Florida, I had a safe deposit box – it was free, after all. So Donna and I kept important things, like passports and World Series tickets, in it.

Donna ran a travel agency and was offered a "fam" trip — vacations that are granted to travel agents by airlines, tour companies, or other affiliates to "fam"-iliarize them with the product— to Rome and Athens, all expenses paid. She happily accepted and asked me to get her passport from the bank.

The trip left on Saturday, so I had plenty of time, but I procrastinated since I was busy. I came home after a long Friday, exhausted. Donna asked a simple question, "Did you get my passport?"

I immediately knew there was no way I could get to her passport, the vault was closed and the timer was set.

So Donna didn't get to Athens or Rome, and we spent a very quiet weekend at home. She was a trooper and never really blew up at me, but she had leverage now. Even though she never used it, we both knew it was there.

Be careful not to pack away all of your clothes on the last night

Usually, Donna and I would pack our stuff the night before leaving the ship and put our bags outside of the door for pick up on the dock the next morning. But one time, she wanted to see the production show and I wanted to finish a TV series, so we parted ways for the evening.

I finished packing and set the bags outside, but I noticed some clothes that Donna had forgotten and dutifully added them to the luggage while she was in the bathroom getting ready for bed.

Early the next morning, I woke up to hear her scream, "Where are my clothes?"

I said that I finished her packing, putting away those clothes she had carelessly forgotten. She calmly explained that the outfit she had left in the closet was for this morning — meaning she didn't have anything to wear except her nightgown. This was not my finest hour.

Fortunately, Donna had worn her good nightgown, so she was decently — if not, appropriately — dressed for disembarkation. We stayed in our cabin as long as could, I threw my jacket over her, and we sauntered off of the ship without drawing much attention.

Don't forget that members of the crew are people, too

Crew members are away from their homes for long periods in far-off lands, among a constant stream of strangers.

They are not supposed to let their own problems show and must smile and be pleasant no matter their own feelings.

So be nice, cheerfully pay your gratuities, and add a few dollars just to make sure. Hear them as they speak of their life at home and their hopes and dreams.

There's no need to confine your travels to a single cruise line

This may be a controversial piece of advice, but I state it freely.

We have sailed with 17 cruise lines, many long departed, but have found the experiences differ in quite a few ways, even within companies.

Since our ship travels began in the 1980s, we've witnessed that cruise lines pride themselves on being different. But what really matters is that you travel with people you love and stay alert to the new friends waiting for you on board.

You'll probably never reach the top tier of loyalty benefits, but you'll have access to a variety of perks not available on a single line.

By switching it up, you'll experience the variety of ships, sizes, ports, cultures, and strengths different cruise lines have to offer. Plus this opens the door to new thrills and adventures.