3 tips for using Google Flights to score cheaper airfare, from travel expert Katy Nastro

When it comes to booking flights, travel experts are just like the rest of us.

Katy Nastro has visited more than 40 countries around the world. For the most part, she finds her flights through the Google Flights search engine.

As a frequent flyer and travel expert at Going, Ms Nastro has a number of techniques she employs to find the best and most affordable flights she can.

Part of what makes Google Flights Ms Nastro’s preferred flight booking destination is the ability it gives her to customize her search.

When she is planning a trip, Ms Nastro doesn’t stop at entering her destination and dates. She’ll toggle settings to sort by nonstop flights and preferred airlines and will potentially set a price threshold.

“I put in all of my filters to make sure that I’m looking at as close to perfection as possible,” Ms Nastro tells CNBC Make It.

Here are three tips from Ms Nastro to book flights like a pro.

1. Flexibility is your friend

Keeping your options open is one of the most important things you can do to help yourself find the best travel deals.

“I think flexibility is the biggest thing people need to remember,” Ms Nastro says. “Google Flights has the functions within it to make it as easy as possible for you to explore all your options.”

For example, Ms Nastro prefers to look at one-way flights rather than round-trip when she is first planning a journey. This is helpful not only for comparing prices, but also for figuring out if she can get as close to her desired flight times as possible.

“If you’re really looking to prioritize travelling more affordably you should open your search up to the idea that you could fly out on your preferred airline but it might be cheaper to fly back on another,” she says.

When she punches in a destination, Ms Nastro doesn’t just stick to that city’s local airport. She adds different airports in the area as well, even if they might be a bus or train journey away from where she wants to go.

“It really gives you the capability to widen your net,” she says.

With more options, you can decide if flying out of your way is worth the savings.

“Do I really want to prioritize my cost savings with the time that it’s going to take me to get to these alternate airports? Maybe. If the cost saving is significant enough.”

When searching for international flights, Ms Nastro is aware that Google may serve her options that have “super long layovers or multi-stop flights that nobody is really looking for.”

To avoid getting her hopes up for a low price on a suboptimal flight, she plans ahead.

“When I’m searching, I’m always making sure that I put in layover duration and toggle which connecting airports I will and won’t fly through,” she says.

“Yes, you might be able to get a cheaper flight if you have a longer layover,” she adds.

“But unless you’re going to be able to leave the airport and have enough time to do so, it might not be worth that time sitting in the airport.”

2. Price history is helpful ... until it’s not

Google Flights has a feature that shows you the pricing history for a flight you’re looking at, as well as predictions of how the price will fluctuate in the future. But be careful about relying too much on this information, especially during a record-breaking travel season.

“It’s tough to say that Google Flights is 100% accurate all of the time,” Ms Nastro says.

“It’s giving you an estimation based on history, which is pretty good, but it doesn’t mean that past history is going to deliver future results.”

Deciding when to pull the trigger and book your flights may depend on when you’re looking.

If you’re in the Goldilocks window — the time frame during which you’re most likely to find the best prices to a given destination — you should feel comfortable booking with the knowledge that prices are only likely to go up from there.

“For peak seasons like the summer, we recommend booking between three and seven months out for domestic trips and between four and 10 months for international trips,” she says.

But if you’re booking on short notice, don’t gamble on a sudden price drop.

“If you’re looking to book a flight in two weeks, it’s probably best to book it immediately if you’re comfortable with the price rather than wait another week,” she says.

3. Don’t turn off alerts after you book

Once her flights are booked, Ms Nastro still keeps price alerts on.

“Because we have largely done away with change fees on legacy carriers in the US, if you booked a main economy ticket you can call and have that flight rebooked at that lower price and then get a credit,” she says.

“I did this the other day and got a credit that I’m going to use towards a flight in August.”

Ms Nastro configures her settings to give her alerts not only for the flight she already booked but for all flights that day for the trip she wants to take.

“It’s likely not the case, but if it’s cheaper to fly on a different airline, I fly enough that it would make sense to pocket the travel credit to be used in the future and then book that cheaper ticket,” Ms Nastro says.

And as much as she prefers Google Flights, Ms Nastro will still check other sites as well.

“Sometimes Google Flights doesn’t display the absolute lowest fair that could be available on a really small [online travel agency],” she says.

“You can use other search sites like Skyscanner or Momondo that could be $200 more in savings.”