If you’ve ever been on a cruise before, you know how fun they can be—living it up with the food and drinks, wind in your hair on deck, and stops at every gorgeous tropical island. What could be better?

Unfortunately, there are certain things on a cruise ship that can make your trip somewhat frustrating. If you aren’t prepared, you might run into one of the top common cruise ship mistakes that many people make.

And if you’ve never been on a cruise ship before, use these mistakes as a guide when booking your first trip. Check them out:

1. Booking your flight the same day the ship leaves.

   No one wants to waste a vacation day—so flying in the same day you’re supposed to leave on the cruise is pretty common. But airlines aren’t the most reliable (and neither is the weather). So if you fly in the same day, you risk missing your ship in the event you’re delayed. Do yourself a favor leave yourself a good 24 hours just in case of delays or cancellations.

2. Booking excursions through the ship.

   When taking a cruise, you probably want to go all out. But if you’re booking any excursions (say horseback riding on the beach when the ship docks, snorkeling, or a dinner in the sand), you may want to research it first. Chances are, if you book it through a different party, you’ll end up with a much better price (and probably a better time too—booking through the ship tends to have times that are pretty early in the morning).

3. Using your cell phone as you normally would.

   Many people forget to turn off data roaming when on a cruise, and then get hit with a massive phone bill. Phone calls, texts, and even checking your Snapchat story can cost you major bucks if you’re not careful.

4. Trying to fit more than two people in a room.

   We get it, we always try to share rooms to save some extra cash too. But bunking up on a cruise ship is probably the last thing you want to do. Why? Rooms aboard a ship are much smaller than your average hotel room. Sometimes they can barely even comfortably fit two people, let alone four or six. (Plus, do you really want to try to brush your teeth in and do your hair in that shared bathroom space with a number of other people?)

5. Expecting Wi-Fi to be included.

   Sure, people in the 90s and earlier were fine—but nowadays, we can’t bear to not be instantly connected to our world of social networks. But Wi-Fi can cost an arm and a leg on a cruise—sometimes around $25 an hour! Plus, the speed of said interwebs when you’re in the middle of the sea can be downright miserable. Be sure to inquire about the cost of Wi-Fi before booking so you’re not unpleasantly surprised later on and forced to disconnect (though we suppose that wouldn’t be the worst thing in the world!).

6. Not expecting that daily service charge.

   Chances are, you’ll be charged a daily service fee for staff who take care of things like room service, room valets, and more. The charge could be upwards of $30 a day, so be sure to prepare for this extra charge in advance.

7. Skipping reservations.

   If you think you can head to any restaurant on board at a moment’s notice, think again. While some restaurants do allow for this, specialty ones probably require a reservation. Be sure to schedule these for early in your trip—if you wait until the end, you might be put on a wait list and not get to try it out.

8. Not keeping tabs on your tab.

   If your cruise isn’t all-inclusive, it might feel that way because nowadays, everything can just be charged to your room. Be sure to count how many piña coladas you’re ordering at the bar—they can add up quickly and you don’t want to be hit with a huge bill (and a huge hangover for that matter).

9. Not being cognizant of the calendar.

   If you’re trying to enjoy a low-key vacation, try to avoid booking your trip during time periods such as college spring break or during summer weekends, when birthday or bachelor/bachelorette parties might be popular. Likewise, if you want a crazy time full of young partiers, don’t book during the holidays or other times when adults are likely to be off of work.

Have you ever made any of these cruise mistakes before? If you’ve never been on a cruise before, what are you most looking forward to when do you go?