A travel expert shares 3 tips for obtaining cheaper airfare using Google Flights.

Just like the rest of us, travel experts also face challenges when booking flights.

Katy Nastro has visited over 40 countries globally, and mostly books her flights through Google Flights.

Nastro, a travel expert and frequent flyer at Going, uses various techniques to find the cheapest and best flights possible.

Nastro prefers Google Flights as her flight booking destination because it allows her to customize her search. While planning a trip, she goes beyond just entering her destination and dates. She adjusts settings to prioritize nonstop flights, preferred airlines, and may set a price limit.

Nastro tells CNBC Make It that they put in all of their filters to ensure they're viewing as close to perfection as possible.

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

1. Flexibility is your friend

One of the most crucial things to do to find the best travel deals is to keep your options open.

"Nastro believes that flexibility is the most important thing to remember. Google Flights offers features that simplify the process of exploring all options."

Nastro prefers to compare prices of one-way flights rather than round-trip flights when planning a journey. This helps her determine if she can get as close to her desired flight times as possible.

To affordably prioritize traveling, consider flying out on your preferred airline but returning on another, she suggests.

Nastro doesn't limit her search to just the local airport when she inputs a destination. She also considers other airports in the area, even if they are farther away from her desired location.

""By expanding your options, you can determine if it's worth sacrificing time to save money on flights to different airports," she says."

Nastro knows that Google may present her with international flight options that include "extremely long layovers or multiple stops that no one truly desires." To prevent disappointment over a low-priced but subpar flight, she takes proactive measures.

She ensures to include layover duration and toggle connecting airports while searching, she states.

"If you have a longer layover, you may be able to get a cheaper flight. However, it may not be worth the time spent sitting in the airport unless you can leave and do something outside."

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

Google Flights offers a feature that displays the historical pricing of a flight you're interested in, as well as predictions of how the price may change in the future. However, be cautious when relying heavily on this information, particularly during a peak travel season.

"According to Nastro, Google Flights is not always 100% accurate because it relies on historical data for its estimates, which may not necessarily predict future outcomes."

Booking flights may depend on when you're looking. If you're in the Goldilocks window, you should feel comfortable booking with the knowledge that prices are only likely to go up from there.

She advises booking between three to seven months in advance for domestic trips and between four to 10 months for international trips during peak seasons like summer.

If you're booking on short notice, avoid taking a chance on a sudden price drop.

She advises booking a flight two weeks in advance, but only if you're satisfied with the price, rather than waiting a week longer.

3. Don't turn off alerts after you book

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

"We have eliminated change fees on legacy carriers in the US, so if you booked a main economy ticket, you can call and have your flight rebooked at a lower price, and receive a credit," she explains. "I did this recently and used the credit towards a flight in August."

Nastro sets her preferences to receive notifications not only for her pre-booked flight, but also for all flights on the same day for her desired trip.

Nastro suggests that it may not be true, but if flying on a different airline is cheaper, it might make sense to use the travel credit for future bookings and then purchase the cheaper ticket.

Nastro will still check other flight booking sites in addition to her preferred Google Flights.

""Google Flights may not always show the cheapest fare on a small online travel agency, but you can save $200 by using Skyscanner or Momondo," she says."

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