This post is part of the Frugal Travel Series. At Frugal Hackers HQ, we apply many strategies to optimize our travel spend, which happens to be our top spending category in the "discretionary spending" category. Follow along to see how we maximize our enjoyment of vacation days given the constraints on time and money.

Studying the airline industry's pricing strategies fascinates me. Operating flights is a hugely expensive undertaking, so airlines have to maximize their earnings on every square inch of the flight. Next time you're waiting at the boarding gate in an airport, take a look at everyone around you.

Everyone gets from the same point A to point B. The cheapest ticket on that flight could be as low as $0, and the most expensive ticket could be as high as $500, $5,000 or maybe even $23,000. Price is not a proxy for value. This is true for flights, and it's true for pretty much everything else in life ;)

The most I've paid for flights is $2,100/person for round-trip flights from SF to Auckland, New Zealand. That was a whopping 55% of our entire trip expenses. We travelled during the Christmas holidays, at the busiest time for tourism in New Zealand. In hindsight, it would've been a better idea to wait for a few more years until we had more flexibility with our work schedules, and then do some slow travel there in February/March, to take larger advantage of our initial flight outlay.

The least I've paid for flights is $0. Most of our flights for the last couple of years have been paid for through reward points from credit card churning.

Most of our trips are somewhere between these extremes. Even when I pay using points, I try to use the tips below to optimize for the cheapest flight. Even if it's "free", Points = Dollars when you think about the opportunity cost.

#1 Plan ahead and avoid busy times

Fly Tuesday - Thursday whenever possible. Here's my list of days/times of the year to avoid:

December Holidays (Dec 20 - Jan 2)
Thanksgiving Weekend
Other Holiday Weekends
Weekends in general

I use Google Flights for my initial price checks on flights. After you input your dates, take a look at the dropdown that shows up with the price calendar. If your date doesn't have a green highlighted price, you're probably paying too much: book farther ahead, or plan to travel in the shoulder season once the high tourist season is over.

#2 Fly economy/coach class

The goal is to get from Point A to Point B. The reason for why you travel lies within what you do at your destination, not how you get there. The longest flights I've taken are usually around ~14 hours. I'm not a fan of sitting in cramped spaces for extended periods of time either. However, business class flights are easily $2,000 or more higher than coach flights, especially on the long haul routes. Saving $2,000 in 14 hours by not upgrading to business class translates to earning $142.86/hour. Not shabby for an hourly rate, eh?

#3 Don't pay for refundable tickets

Refundable tickets cost more since the airline has to accept the risk that you will cancel at the last minute and leave a seat unoccupied. The flip side of this for passengers like you and me is that we bear the risk of cancellation. 3 things to keep in mind every time you buy a flight ticket:

Double check every detail in your booking - name, date of birth, departure time and date, arrival time and date, departure airport, arrival airport, layover time etc.
You have 24 hours to cancel a flight from the time of booking (this is true in the USA, not sure if it applies all over the world)
Our Chase Sapphire cards give us free trip cancellation insurance. They do have some restrictions around when this applies, so be sure to read the fine print.

#4 Take a longer layover

The more complicated and longer your layovers are, the cheaper your flight tends to be. If you have the Chase Sapphire Reserve card, you get access to the Priority Pass card which allows complimentary access to airport lounges all over the world with free food, drinks, shower, and internet. This makes layovers significantly more tolerable.

#5 Subscribe to Scott's Cheap Flights

If you have some flexibility around when you can take vacations, Scott's your new best friend. He finds amazing deals and shares them through his mailing list. Sign up at Scott's Cheap Flights with your email address and get ready for awesome flight deals coming your way.

Not exaggerating here, these are some actual emails I've received in the last few months.

Interestingly, I booked all my flights this year after seeing one of Scott's emails. Neat savings!

#6 Look up prices for airports nearby your city

The biggest airport near you might also be the most expensive one. Some of the cheaper airlines prefer to fly in and out of smaller airports to save on landing and gate fees. For example, Allegiant Air which offers $100 round trip flights to Bellingham, WA (one hour drive from Vancouver, BC), only flies from Oakland (OAK), not SFO. To make sure you see the best flights around you, make sure you select nearby airports in your flight searches. Here's a screenshot from Google Flights showing how.

#7 Compare prices across several websites

This one's self explanatory. Flight prices can and do vary across different websites. It takes only a few minutes, and even if you don't find anything cheaper, at least it'll give you some peace of mind that you're not overpaying. I always check Google Flights, Priceline, Skyscanner, Expedia, Kayak, Cheapoair and Momondo. I also check pricing on the airline websites directly. Some airlines like Southwest don't always show up in these aggregators, so it's worth popping over to their own websites for a quick check.

#8 Volunteer to take the next flight

Airlines usually sell more seats than are available on the flight because there's an expected % of passenger no-shows. If your flight is oversubscribed, airlines will usually pay $200 per person to have you take the next flight. This might require you to not have any checked baggage, so that's another reason not to pay for checked bags. You might also have to show up early to put your name down as a volunteer, so it's worth getting to the airport ahead of the boarding time. If you get bumped to the next flight, you can go check out the free Priority Pass lounge in your terminal as you wait if you have the Chase Sapphire Reserve credit card.

Right after our wedding, we were headed to Iceland for our honeymoon via London. We found out at the airport that the British Airways flight to London was overbooked. Thankfully we had a long layover in London, so we volunteered ourselves to get rebooked onto a different flight. Our names were at the top of the list since we arrived at the airport super early, and they gave us the equivalent of $850 Canadian Dollars to take a different flight to London. We did have one extra stop, but we gladly accepted that for the free cash!

#9 Use award tickets

Award tickets are reserved for members of airline loyalty programs and they can be redeemed by spending airline miles. Signing up for most loyalty programs is free, and you collect miles each trip by entering your membership ID at the time of booking. You can also convert your credit card points into airline miles.

Here's an example of award ticket cost vs. regular cost for the exact same flight from San Francisco to Newark (NYC). The regular price from United.com = $286 (screenshot on the left below). On the right, the total cost for the award ticket is presented as miles + dollars. For comparison, the miles convert at a ratio of 100 miles to $1, so total cost for the award ticket is $125 + $80 = $205. Savings of $80 in your pocket, cha-ching!

#10 Take advantage of credit card rewards

I've saved the best for the last! Chase has some credit cards with fantastic sign-up bonuses, and Mr. Frugal Hacker has written an entire post dedicated to our long-term strategy of credit card churning. In addition to points, credit cards can also come with other useful travel rewards.

UnitedMileagePlus card gives you one free checked bag
Chase Sapphire Reserve gives you and a +1 free access to premium airport lounges via Priority Pass
Trip cancellation and purchase protection
Rental car collision damage insurance
3x points on travel, effectively getting a 4.5% discount on all travel-related purchases including flights

So there you have it, 10 of my top frugal flight hacks! Did I miss one of your favorites? Please share in the comments below!