7 secrets of booking a cheap flight, from a family that has been traveling the world for over 3 years

In May 2012, Erin and Josh Bender sold their cars, rented their home in Perth, Australia, and booked a one-way ticket to Bali for themselves and their two children, Mia, now 6, and Caius, 5.

What started as a "six-month adventure" turned into much more, they tell Business Insider. Today, nearly four years later, they're still traveling nonstop around the world.

They've been to over 60 countries as a family and have booked about 40 flights along the way.

They've also become quite savvy savers: "The first year of travel, we ended up saving $40,000," they say. It was a combination of staying in more affordable countries - they spent half the year in Asia, where cost of living is much lower than in Perth - mindful spending, and not having to cover expenses such as utilities, gas, internet, and car insurance.

"Flying is the most expensive part of travel, but it doesn't have to be," Erin writes on their blog, "Travel With Bender." She also shares their secrets to finding cheap flights. Here are some of our favorites: