The secrets to a hassle-free summer vacation seem simple enough: Keep a checklist. Read the rules, especially if you’re flying. Take photos of your rental car. Don’t make assumptions about your hotel. And remember your paperwork when you’re traveling overseas.

But simple as that sounds, in practice it’s not always that easy. Here’s how to be a smart traveler:

Be prepared

The smartest travelers plan ahead and have a fondness for checklists. Did you pack the right clothes? Remember all the power cords? Your passport?

Lists are your friends. Smart travelers know when to wing it and when not to. Sure, your friends and family might poke fun at you for keeping a list for everything, but they’ll thank you when you’re the only one with a power adapter in France. Travelers who keep lists are far less likely to get into trouble on the road.

Read those airline rules

Airline policies can be counterintuitive, even bizarre. For example, a one-way ticket can sometimes cost more than a round-trip ticket on the same plane. A change fee can exceed the actual value of a ticket. Also, “nonrefundable” means nonrefundable, except when it doesn’t.

Confused yet? If it’s any consolation, even airline employees sometimes get mixed up about their own rules.

Kelly Hayes-Raitt remembers seeing an unbeatable deal for a flight from Los Angeles to Tampa, Fla. But when she arrived at the airport, she noticed her itinerary. “The plane landed in Phoenix, Dallas, Houston and New Orleans before finally arriving in Tampa,” remembers the writer from Santa Monica, Calif. “I still groan when I think of how stupid I was.”

Take photos of your rental car

Take “before” and “after” pictures of your rental car. Some customers allege rental companies have built a profitable business by charging you big bucks for small damage, and the only way to avoid a repair bill is to show an “after” image of your undented car.

If you are charged for damage you didn’t do, sometimes a brief, polite email to the company will get the resolution you want — if you copy the right people (such as your state’s attorney general).

ASSUME NOTHING ABOUT HOTELS

No segment of the travel industry — except perhaps the airlines — profits more from our collective ignorance than hotels. They would like you to think they’re the only lodging option in town, but they’re not. Today’s accommodations cover the spectrum, from glamping to vacation rentals. Don’t lock yourself into a traditional hotel or resort, at least not without first shopping around. You might be able to find a bargain on Airbnb.com with a better location and fewer hassles.

Travelers make other assumptions about their accommodations that aren’t necessarily true, too. For example, you’d imagine that the room rate you’re quoted is the room rate you’ll pay, maybe not including sales taxes. But don’t forget about daily resort fees, normally disclosed just before you push the “book” button — so don’t thoughtlessly click through. If you see a fee you don’t like, stop and look elsewhere for a room.

REMEMBER THE PAPERWORK

Having the right visas and permits and an updated passport is your responsibility, no two ways about it. That’s a difficult message for many travelers to hear. They rely on the advice of a travel agent or what’s posted on a website and believe (incorrectly) that those third parties should reimburse them when something goes wrong.

This is especially common in the case of cruises, where a birth certificate, instead of a passport, is often enough to board a ship.

The consequences can be heartbreaking. A worried mom from Sacramento, Calif., contacted me because her daughter and son-in-law, en route to their honeymoon in St. Lucia, had been stopped at the airport and denied boarding. The reason? The bride’s passport was due to expire soon — too soon for her to be allowed into the country. Some countries require your passport to be valid for six months from the date of your entry.

An alert travel agent might have caught the problem, but now it was too late. And without travel insurance, the entire trip would be lost.

“Can this trip be salvaged?” the mom wrote to me, with only hours before the vacation was to have begun. Sadly, it couldn’t be.

Christopher Elliott’s is a consumer advocate and author of “How to Be the World’s Smartest Traveler” (National Geographic). His column runs frequently at seattletimes.com/travel. Contact him at chris@elliott.org.