I've worked on cruise ships for years. Here are the 14 common mistakes I see passengers make.

• I've worked on a cruise ship for six years, so I've seen a fair share of passengers make mistakes.
• Missing the ship at port or booking excursions with outside operators could be costly and risky.

After over six years working on ships for a major cruise line, I've witnessed tons of travel blunders that prevent guests from having the best possible experience.

Here are 14 common mistakes I see travelers make:

Not reading the fine print can lead to conduct issues later

Passengers usually come on the ship excited for a good time, and for many, this involves a drinks package.

Having fun and enjoying your vacation is one thing, but getting too rowdy is not allowed.

Every passenger consents to a hefty conduct policy when they book the cruise, so make sure to read through it to know what's prohibited on board.

I've come across a few troublemakers who had no idea that smashing Champagne glasses in the hot tub could get you booted off the ship.

Make sure to put your phone on airplane mode to avoid expensive roaming charges

Cellular rates at sea can sneak up on you, and you can easily rack up a $500 roaming bill.

Even if you're not actively on your phone, most are still using data, so make sure to set yours on airplane mode to avoid roaming charges.

Really, unless you're using your phone for photos or accessing the ship's WiFi, just turn it off.

Many passengers don't take advantage of the different dining options on board

I often see passengers eat all three meals at the buffet every day. I know some people just really love the self-serve option, but it surprises me how many guests have no idea what's included with their trip.

Many times, the biggest shock to most first-time cruisers is that the dining room is included. Yes, this means a sit-down meal where you can order seven appetizers, five entrées, and 12 extra cookies for a midnight snack.

There are also so many free-food spots around the ship, like the pizza station, 24-hour ice-cream machine, and small cafés.

Just be aware that specialty dining, like the steak house, might cost extra.

Leaving your room key behind is more of a hassle than you'd expect

It is not just a room key — it's your onboard credit card, ticket on and off the ship, and identification for the week.

Everything is connected to that card, so make sure to set up your information online ahead of time to start swiping the moment you get on board.

Security will scan it when you pass through the gangway to know who is on or off the ship, so it's especially important to have on port days.

If you lose it, report it to the service desk right away to make sure no one else spends your money.

Many guests don't know that they can bring their own wine on the ship

While many people think no outside alcohol is permitted on the ship, many major cruise lines allow passengers over the age of 21 to bring a bottle or two of wine on boarding day, so you can stop smuggling drinks in empty mouthwash bottles.

Some terminals will even sell wine to boarding travelers.

If you buy alcohol in a port, you'll have to check it upon reentering the ship, and it'll be delivered to your room on the last night.

You might miss out on fun events by ignoring the cruise planner

An updated cruise planner is placed in your room every night for the next day. Many passengers overlook it, but it can save you a lot of time and money.

It contains important information like the hourly activities, the weather, special happenings, the drink of the day, and information on the ports.

Missing the all-aboard time on port days is an expensive mistake

In my years of working cruises, I have seen more than a handful of guests miss the ship.

While this is a huge fear for most passengers, it usually happens to avid cruisers — people who have been to the port many times before sometimes assume the all-aboard time is always the same.

But this time varies by cruise, and it's stated on multiple signs at the exit gangway, in the daily planner, and in the captain's announcement.

Also, always triple-check whether the all-aboard time is based on the ship's clock or the local time.

If you miss the ship, you'll have to get yourself to the next port, which can be very pricey.

Passengers miss out on discounts by not booking their next cruise while still on the ship

Booking a future vacation while cruising can get you bigger discounts, access to new itineraries not open to the general public yet, and a lot of onboard credit.

These booking appointments are usually filled up by the last few days of the cruise, so head there at the beginning of your stay for more deals and no wait.

Booking a tour with an outside operator can be risky

Although it might be a lot cheaper to book your tours independently, it's also a lot riskier.

The onboard excursions through the ship are with verified operators. And most cruise lines will wait for the ship's tour to return before leaving the port, even if it's hours late.

But this is not the case if you book on your own, and running through the port to find the ship sailing away is probably not the excursion you're looking for.

Immediately removing the automatic gratuity affects many staff members

On most cruise ships, there is a preset daily gratuity charged per passenger unless it's removed at the guest-services desk.

I see so many people come on board and immediately remove the charge, but this fee is usually split between your housekeeping, dining, and cleaning staff. It is essential to their jobs and affects their livelihoods.

I'd recommend waiting until the end of the cruise to make sure you're happy with the service instead of removing it on day one. You can also increase or decrease the amount instead of cutting it.

Packing prohibited items can lead to a headache

As confident as you are that you can sneak on your portable iron, I seriously advise against packing anything that's not allowed on board.

Security scans your bags on embarkation day, and if a prohibited item — like an iron, a bottle of vodka, or a candle — is found, they will hold your bag.

Your luggage won't be delivered to your door, and you'll have to wait several hours until security contacts you, brings you to the holding area to search the bag, and confiscates the item until the end of the cruise.

Prepare your necessary travel documents to avoid trouble at ports

Cruise ships journey all over the world, so make sure to check if you need specific visas or documents based on your nationality.

You are responsible for knowing and bringing your own paperwork. If you don't have the right documents, you might not be able to get off at a port or, even worse, be allowed back on the ship.

I saw this happen when traveling to India with many American guests, a handful of whom didn't realize they needed a visa.

Dressing down on formal night limits your dining options

Even though walking through the promenade in shorts is your choice, many guests aren't aware that there's usually a formal evening on cruises.

Most passengers don evening gowns and suits on formal night, and I've met cruisers who wished they would've packed at least one nice item — besides their Margaritaville shirt, of course.

Passengers not formally dressed on this evening aren't allowed to eat in the main dining rooms, though the buffet is open to everyone.

It's worth learning the difference between port and starboard

Different announcements will direct passengers to either the port side or starboard side of the ship, so it's best to brush up on the jargon before your vacation.

Port is the left side of the boat and starboard is the right, always configured facing the front of the ship.

Just remember that "port" and "left" are both four letters. You'll thank me later.

Click to read more of my advice on cruising and stories from onboard the ship.