A bad travel experience can waste your money as well as your time. And a good number of irate consumers get ahold of Christopher Elliott: He’s the consumer advocate for National Geographic Traveler and writes its Problem Solved column as well as his own syndicated Travel Troubleshooter column.

Elliott’s book — “How to Be the World’s Smartest Traveler (and Save Time, Money, and Hassle” — was published this spring ($19.95; National Geographic. Kindle edition: $9.19).

Q. Your Travel Troubleshooter column deals with complaints. Your book has a broader consumer focus — from buying luggage to managing your vacation cash. Why is this?

A. I’ve always tried to help solve consumer problems wherever they are, so this was a natural extension of my mission. I still write about the dust ups I’m known for — the missing refunds, the lost reservations, the scammy travel offers. But that’s just one part of the travel experience.

Actually, if you want to find the pain in travel, you have to read the contract. In the past, the written agreements offered by travel companies protected both them and you, the consumer. Now, the documents just protect companies. They’re classic adhesion contracts that apply to you, but not the company.

That’s one of the reasons I say in the book that you really have to read the fine print. It’s what often causes you so much pain as a traveler. And it’s what keeps me employed as a consumer advocate.

Q. Your self-help tips are for preventing problems. What’s the biggest issue?

A. The most common complaint I hear is, “I wasn’t aware of the rules.” Many readers travel infrequently, so maybe they don’t know about some of the rule changes that have taken place during the last few years, almost all of which are to the detriment of passengers and guests.

For example, if you took your last flight before 2009, you could check a bag at no additional charge. Now you have to pay for the first checked bag on most airlines. More hotel rooms offered online are completely nonrefundable. If you try to change your dates, you lose everything.

Too many of my readers are stuck with a product they can’t use — a ticket, an insurance policy, a canceled car reservation because the plane was late. That shouldn’t be happening, of course.

Q. And airlines are the biggest offenders?

A. Absolutely. They have multiple contracts that are often so difficult to read that even their own employees don’t understand them. There are separate contracts for international and domestic travel, separate agreements for luggage and fare tariffs in terms of actual fares. You almost have to be a lawyer to know what you’re getting when you’re flying these days.

Q. Are there problems you’ve personally had?

A. I feel that way, because I take my work home with me. I’m on the phone with travelers on the weekend, trying to help them. When something happens to them, it happens to me. But honestly, what this has done is make me much more careful about where and when I travel. I’m really careful when I go anywhere. I keep a packing list and I give myself plenty of time.

But yes, I’ve personally made a mistake or two. That’s one reason I say in my introduction that I’m not the world’s smartest traveler. I once arrived at the airport to fly from London to Vienna on the wrong day. I didn’t check the date on my ticket. Technically, I was a no-show, and the airline could have kept my money. But I was also holding an 8-month-old baby, and the ticket agent was compassionate, and rebooked me on the next flight at no extra cost. Thank you, British Airways.

I’ve also tried to check in on the wrong day. It’s so easy to get your arrival and departure dates mixed up, or to be confused by the date format, which is different for Europe.

Q. Are you the ombudsman of last resort?

A. I hope not. I’m working on an insurance case right now about frequent-flyer miles. A man’s wife became sick in Australia and they had to return early. They had insurance for their trip. I contacted the insurance company and they refunded his policy, but didn’t pay his claim. He appealed to his state insurance commission — I recommend this in the book. The commission made an inquiry and the insurance company cut him a $12,000 check.

I’m just a rung on the ladder, and not always the top one. And this is a team effort. I have volunteers who work with me and I sometimes refer cases to other consumer advocates.

Four years ago, I founded a group called Travelers United, which is trying to change some of the bad policies that affect travelers. We’re launching June 1 as a full-fledged membership organization based in Washington, and I’m very excited about that.

Q. The book has a section on drive trips. What are things to watch out for?

A. With car rentals, frivolous damage complaints are at the top of my list. Car agencies can’t make money with a base rate of $19 per day. The service counter you walk up to is actually a sales counter offering fuel-purchase options, GPS, optional insurance and more.

Damage claims are said to be a profit center for some car rental companies. They’ll go over your returned car with a fine-tooth comb and charge you if they see a ding or dent. This fee suspiciously comes to slightly less than $500 — just below your deductible, so your insurance company doesn’t get involved. You pay $495 out of pocket; they allegedly put the car right back on the lot and later collect on the same ding if they want.

My biggest complaint from readers is probably about GPS directions that didn’t work. I recommend packing an actual paper map.

Q. You also cover cruising. What’s the top consumer gripe?

A. The biggest hassle is with an all-inclusive experience, where you get on a ship and think you don’t pay for extras. If you think most cruises are like that, I would encourage you to get up early on the day of a ship’s disembarkation; go there with a cup of coffee and listen to the arguments between passengers who are checking out and the cruise line’s agents standing behind the counter. Sometimes they’ve paid two or three times what they thought they would because of photos, food or other “extras.” Cruise-offered shore excursions can be expensive. You can find a comparable shore trip for half the price.

Cruise lines are making a ton of money from what it calls “ancillary revenue” — money that isn’t coming from its base cruise fares.

The lengths to which a cruise line will go for your (extra) dollar are pretty extreme. I heard from a woman who was in a ship restaurant and who had asked for the end piece of the roast. She said she was told, “That’ll be extra.”