Air travel is stressful enough without getting to the airport and discovering that your reservation is not valid. If you do decide to book your flight through a third-party travel site, avoid clicking on links that show up in your search results as paid ads, Greenberg advised on his site. Additionally, it's important to be able to differentiate between totally legitimate aggregators and sketchy third-party sites: While the former basically culls a list of prices directly from the source, third-party sites may offer too-good-to-be-true deals. If you do take a chance on a third-party site, always call the airline directly to confirm your reservation.

In 2018; getting a letter in the mail offering you cheap airfare on a major airline is a red flag. "You receive an official-looking letter — on official-looking letterhead from what appears to be a well known airline — claiming that you 'have qualified for an award of two round-trip airline tickets. Congratulations. These tickets are valid for travel anywhere in the continental U.S. from any major international airport. The retail value of the award is $1400…'" Greenberg explained. In general, these types of communications are scams, and you should always call an airline to verify any offers that seems too good to be true. Because there really is no such thing as a free lunch.

So you uncover the deal of the century while searching for airline tickets online, and you call the number listed to verify that the price is legit. This is a good idea. However, if the person on the phone pressures you to book the flight ASAP so you don't miss out on the deal, that's a pretty big red flag, according to the website Best Travel Tips. If purchasing a flight starts to feel like buying a used car, don't do it.

Maybe you get an email asking you to confirm your flight, but it's not the flight you booked. What should you do? According to Consumer Reports, clicking on emails for things you din't actually purchase could infect your computer with viruses or malware. "Never click on a link to your online accounts through email or call an account-related phone number in a text message someone sends you. Instead, open your PC or mobile web browser and type in the desired address on your own," Consumer Reports advised. "And don’t click on an email attachment unless you’re expecting it."

OK, buying anything off of a site like Craigslist is a gamble, but you should never buy a plane ticket via a Craigslist advertisement. According to the website Scam Detector, scammers buy plane tickets using stolen credit cards, then they post the tickets on sites with a message that they can't take the trip but they're willing to transfer it to you for a deal. "They reveal the confirmation number so the victims really think everything it's legitimate. The purchasers are then required to transfer the money into an untraceable account, by wiring money through services like Western Union," Scam Detector explained. "When the victims try to redeem the tickets with their credit, they are told they can't because the initial tickets were bought with a stolen credit card."

You've likely seen those posts on Facebook that claim you can enter to win free airline tickets if you comment on and share the post. Hardly anything in life is free, and this scam can end up costing you a lot in the long run. On its blog, Hemidal Security noted that the best outcome of this scam is that nothing happens because the faker was trying to gather a large number of likes, which is called "likejacking." The worst case scenario is pretty scary: "Cyber criminals now have access to valuable data: your name, address, favorite activities, and maybe even a password," Ana Dascalescu explained on the blog. "If you are like most internet users and have the same password across multiple accounts (something you should never do!), you are now vulnerable to social engineering. You are also exposing your other online accounts to a great deal of risks."

By the time you realize this one is a scam the third-party cyber criminal already has your credit card information, including the expiration date and three-digit security code. According to the eCommerce Times website, this scam takes you all the way through the payment process for your cheap flight then returns and error after you hit send. At this point a message pops up instructing you how to pay with a money order. Don't do it. Promptly call your credit-card company and tell them your card has been compromised and you need a new one with a different account number ASAP.

This is similar to that Facebook messenger scam where a hacker impersonates one of your close friends, claims to be stranded, and asks you to wire money ASAP. Or, that email scam where someone tells you you've inherited a zillion dollars from a prince, and you just need to provide your bank account number so they can transfer you the money. If a third-party airline site requires you to pay via wire transfer, you're not only not going to get a flight, but you'll never see that money again. In 2018, every reputable site should accept credit cards.

The first thing you should always do before entering any personal or financial information on a third-party travel site it to verify that the site is secure. Secure websites will always have the prefix "https" versus non-secure sites that use "http." Most browsers will notify you when you visit a website that's not secure, but it's always good to double check. Some of these fraudulent sites can look just like reputable sites, which means you might think you're buying your flight from a trusted travel site when it's actually a sophisticated replication of the site.

The good news: If you do end up getting scammed and you paid via credit card, you can get your money back. "After you make an online reservation, always call the company afterward to confirm. If there is no record of your reservation, it’s better to know sooner rather than later," the Norton security blog advised. "You’ll be able to alert your credit card company, report the fraud, and still have time to book reservations with the real deal."