I book dozens of flights a year with an easy strategy to save thousands of dollars on international airfare

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• Airlines often charge more for a one-way flight than a round-trip.
• You can save hundreds of dollars by booking round-trip or multi-city itineraries instead of one-way flights.
• Even if you only need a one-way flight, you can save money by booking a round trip and forfeiting the return flight.
• Read Insider's guide to the best credit cards with travel insurance.

While planning a recent trip to South Africa, I stumbled upon an unbelievable deal. Round-trip coach fares from my rinky-dink home airport to Johannesburg were available for just $300.

That's a fire sale price. One-way flights for the same dates cost over $1,000 each way. But I didn't want a round-trip; I wanted to hopscotch my way north and return from Europe. So I did what any tight-fisted, fallible mortal would do: I booked the cheap round-trip flight with no intention of using the return leg.

Airlines aren't a fan of this behavior — and some even reserve the right in their terms to penalize you for it. Still, their pricing models often incentivize the practice. I don't make a habit of this, but a solid $700 in savings is entrapment.

If you're on the prowl for summer travel, you need to know this tactic for securing cheaper airfare. We'll look at real examples — and how to use this strategy in a way that doesn't tatter your moral fiber.

We're focused here on the rewards and perks that come with each card. These cards won't be worth it if you're paying interest or late fees. When using a credit card, it's important to pay your balance in full each month, make payments on time, and only spend what you can afford to pay.

Book round-trip vs one-way to save money

For most situations, I'm fiercely pro-one-way flights. Here's why:

• If you miss your outbound flight, your return flight won't be affected. You can still use it, change it, or cancel it.
• You can create as many stopovers as you want. If you'd like to visit multiple countries, it's inconvenient to have to return from the same airport you flew into.
• When booking free travel using rewards, you can use different points currencies on a single trip (like flying American Airlines there and United Airlines back).

If you're like me, you begin your planning with one-way searches. If prices are too much, you may find round-trip flights that cost less than a one-way.

For example, a one-way ticket later this year between Indianapolis and Dublin costs $1,063.

A return flight for the following week costs $794, making this specific itinerary cost a whopping $1,857.

But if you book the same dates as a round-trip itinerary instead of two one-ways, the lowest price is $1,055 on American Airlines. That's $8 cheaper than a one-way ticket — and more than $800 less than purchasing separate one-ways.

Multi-city flights get similarly discounted results

Those looking for one-way flights often plan to visit more than one destination. If your initial one-way searches are returning dry-heave prices, try a multi-city search (sometimes called an open jaw). It's usually an option beside "one-way" and "round-trip" on most search engines.

For example, say you want to land in Dublin and return from Madrid. Two one-way tickets cost over $1,900. But by using the multi-city tool, you'll pay as little as $1,060.

Pay for flights using a credit card with travel insurance

Credit card travel insurance has saved me thousands of dollars, between being reimbursed for meals and hotels when my flight's been canceled, or receiving a $500 check to buy clothes when my bag was delayed multiple days.

To be covered, purchase airfare with a credit card that offers travel insurance, like the Chase Sapphire Reserve® and Chase Sapphire Preferred® Card. Chase Sapphire travel insurance is some of the most generous of any travel credit card. These cards also offer travel-specific benefits that even a casual traveler will appreciate — I've had my Sapphire Preferred for eight years and I'll never cancel it.

What to know about booking round-trip vs one-way flights

You'll find that many international one-way fares are priced (seemingly) arbitrarily higher than return fares on the same route — often by hundreds of dollars. If you're traveling with a group, you could easily save thousands of dollars by booking round-trip flights instead of one-ways.

Two caveats:

• The above strategy is not a firm rule. It's certainly possible to find inexpensive one-way fares.
• This primarily applies to international travel. On domestic flights, one-way prices tend to be less inflated. In other words, two one-way tickets are often competitive with a round-trip ticket.

Remember to use a travel rewards credit card that provides insurance — just in case something goes awry during your journey.