I'm a Travel Planner Who's Been on Over 25 Cruises. Here Are 9 of the Biggest Mistakes I See Cruisers Make. The No. 1 mistake cruisers make has nothing to do with the cruise at all. It's about your flight.

This story originally appeared on Business Insider.

Flying in the same day your cruise departs from the port can be a recipe for disaster.

Take in consideration the travel time between your plane terminal and port terminal. Jennifer Greene

If your cruise departs at 4 p.m., don't schedule your flight to arrive that morning. That's the No. 1 mistake I see my clients make.

There's so much uncertainty with air travel, and one minor issue could cause you to miss the boat. You also need to factor in getting your luggage and traveling to the cruise terminal from the airport — some terminals are 15 minutes away and others are over an hour.

Pro tip: Fly into your port city the night before you set sail. It allows you to have a more leisurely morning getting to the cruise port. If you're changing time zones, it also allows you to adjust before setting sail.

Don't miss out on must-dos by booking your cruises for the wrong season.

The time of year you cruise is just as important as the activities you plan. Jennifer Greene

Timing is everything when it comes to cruising — when you go is just as important as where you go.

If your bucket list has whale-watching in Alaska on it, take an August cruise. To avoid hurricanes and large crowds, visit the Caribbean during winter months.

Rather than choosing dates at random, schedule your cruise intentionally so you can make the most of your time at each destination. Working with a travel professional can help if don't want to do the research yourself.

Some guests forget to check if their cruise is all-inclusive ahead of departure.

Certain excursions can have additional fees. Jennifer Greene

Although there's usually a lot included in cruise fares, it's certainly not always an all-inclusive vacation.

Depending on your cruise line, some restaurants, activities, and excursions come with additional fees. You'll probably need to budget for those ahead of time, so make sure to check what's included in your package.

For example, many guests don't consider the beverage cost and have total sticker shock when the bill comes.

Skipping out on travel insurance can also end up costing you later.

I don't think you can ever be too safe when getting travel insurance. Jennifer Greene

Travel insurance can protect your hard-earned vacation dollars, should you need to cancel your trip. Even when you don't think something will happen, unfortunately, sometimes it does.

It's also essential to ensure that you're covered for any medical situations that can occur while traveling or on a cruise.

Researching the best travel-insurance plan is also something I've helped my clients with.

Cruise rooms are small, so don't overpack for your trip.

Your bathroom will probably be on the smaller side. Jennifer Greene

While thinking about what to pack, don't skimp on the necessities. Be sure to pack medicine, specific products, and anything else you need that can't be bought on board.

But keep in mind that bathrooms are small, so don't pack your entire makeup bag either. Just bring what you need.

If you're going to the Caribbean, you might not need a heavy jacket or boots. But you might need those things for an Alaskan cruise. And it's helpful to always check the dress code for restaurants and formal dining nights so you're prepared.

Pro tip: You'll probably do a lot of walking on the ship and on excursions, so pack a comfortable pair of sneakers or sandals for daily wear.

It's usually better to buy wine by the bottle instead of the glass.

You can still enjoy alcohol in a financially responsible way. Matt Hochberg/Royal Caribbean Blog

Without a beverage package, ordering wine by the glass every night can get expensive.

But if you buy a bottle and don't finish it, I've been able to ask the server to recork it and save it for me for the next evening. It's a pretty simple way to save a little bit of money.

Pro tip: Some cruise lines also allow you to bring two bottles of wine per stateroom.

If you don't book certain add-ons in advance, you might miss out.

Cruise lines sometimes offer discounted rates for booking drink packages in advance. Jennifer Greene

If you absolutely want to secure a certain shore excursion, find out how far in advance your cruise allows you to book the experience and try to make the reservation that day.

You don't have to plan your cruise down to the minute, but some things are worth booking in advance. Sought-out dining venues, spa times, and cabana rentals sell out quickly. If you wait to book until you board, you might be left on a waitlist.

Pro tip: Sometimes cruise lines offer discounted rates on drink packages, Wi-Fi plans, and shore excursions if you book ahead of time.

I always recommend that my clients bring cash on cruises.

Cash tends to be helpful to have for tipping. Jennifer Greene

There are ample opportunities to tip on a cruise, so small bills come in handy.

When you're in port, it's also usually best to have cash for local markets and small vendors. Some merchants charge a card fee on top of the price, so cash tends to get you the best deal.

You'll also need cash if you plan to gamble at all. Every cruise ship I've been on, with the exception of Disney Cruise Line, has had a casino.

Make sure to pick the right trip for your vacation plans and needs.

Selecting the right cruise ship is vital for a great vacation. Jennifer Greene

Not all cruise ships are the same, and choosing the wrong one could ruin your vacation.

The ship is going to be your home for a week or longer. Determine what amenities are important to you, if you a prefer family-friendly option, or if you want a low-key kind of vibe.

With so much variety, there's a cruise line to suit everyone's needs, and the industry is continually expanding to include niche markets.