“How can you afford to travel so much?” We’re asked that question pretty frequently, and it’s one that has a lot of answers. Travel is our hobby, so we prioritize our budget accordingly — we don’t ski, sail, or golf (much). We make do with the old couch, drive a 16-year old car, tolerate our temperamental oven, carpool, pack lunches for work every day, keep the thermostat down low at night, and stick to basic cable (although not having ESPN’s Baseball Tonight during fantasy baseball season can be a bit of a sticking point).

When we do travel, we stick to budget accommodations that adhere to Rick Steves’ travel philosophy: “never sacrifice sleep, nutrition, safety, or cleanliness in the name of budget.” (Okay, we’ve missed the target once or twice.)

But our biggest travel-dollar-saving secret isn’t such a secret. It’s frequent flyer miles. We’re not as hardcore as some frequent flyer mile junkies, but we keep our eyes open for easy ways to accrue big piles of miles.

Most airlines offer a sign-up deal for their credit card that includes enough frequent flyer miles to get a free domestic airline ticket. While many of these offers waive the card’s annual fee for the first year of use, some charge a nominal fee (the last card we applied for had an $89 fee). Rather than balking at the fee, we see it as a coupon for an $89 round-trip ticket to anywhere in the US.

Banks do run a credit background check when you apply for the credit card, if that’s a concern. Some cards award the miles (25,000 miles in most cases) after one purchase, while others require a minimum amount of purchases during the first few months of cardmembership (perhaps $1000 over a three-month period).

To meet the requirements, we’ll make a token purchase — something we’d already buy, like gas or groceries — or exclusively use the new card for all purchases until we’ve met the minimum requirement. Then we file the card away to collect dust.

Long after we’ve received our mileage bonus, the card renewal will show up — along with its annual fee — and we can then decide if we want to keep or cancel the card.

We tend to favor cards affiliated with airlines that better service our frequent destinations (United to Chicago and American to St. Thomas, for example), that seem to have better frequent flyer seat availability, or that offer additional cardmember benefits (companion fare certificates or elimination of checked bag fees). We’ve found that, in some cases, savings from the latter can more than make up for the card’s annual fee.

While there’s a school of thought that urges frequent flyers to stick to one card affiliated with one airline, we prefer not to put all of our frequent flyer mile eggs in one basket. Besides, the incremental miles that we accrue with each month’s purchases tend to pale in comparison with the 25,000 or 30,000 or 40,000 mile bonuses offered by some airlines.

As for accruing miles, we use our credit cards for all everyday purchases. (Our checkbook tends to accumulate a lot of dust.) Groceries, gasoline, Internet, insurance, utility bills, charitable donations, meals, parking meters — if they’ll take a credit card, we’ll use it. This isn’t to say that we blithely say “charge it for the miles” and then wince when we get our monthly statement (okay, once or twice!). We stay within our monthly budget, use the credit card instead of using cash or writing checks, and —  this is key — we pay off our balance in full every month. That way, from our budget standpoint, our expenditures are no different than if we’d written checks or paid in cash.

And as for using those miles? It can be tight. Really tight if you’re competing for those very few frequent flyer seats that everybody wants, say on the first Friday of spring break out of PDX or the weekend after Thanksgiving out of, well, any US airport.

We’ve developed a militant philosophy to maximize our chances of scoring frequent flyer seats: plan ahead. We’ll often book our Christmas flights in January and our March spring break flights in April!

Most airlines release their seat inventory 330 days in advance, including their “FQTV” seats. So, we strive to make our travel plans a year or more in advance. Recurring calendar dates like holidays and spring break make it a bit easier.

Once we’ve made our destination decision, we’ll mark our calendar for the date that’s 330 days in advance of our departure. A few days before that date, we’ll start to monitor the airline’s website, trying to pinpoint the time of day that they release the FQTV seats (usually between midnight and 5 a.m. Pacific time).

The last two times we booked FQTV seats, I stayed up until 11 p.m. the night before the magic 330-day mark to see if seats had been released. They hadn’t.  I set an alarm for midnight, pulled my laptop up onto the bed, and checked again. No dice. I tried again at 1 and again at 2. Nope. At 3 a.m. the seats were available! I hopped out of bed, booked our free tickets, and savored the remaining hours of uninterrupted sleep, knowing that I’d saved hundreds of dollars in airfare! (Erin thinks I’m crazy. But she doesn’t complain about the free tickets.)

Are you a frequent flyer mile collector? What are your strategies for cutting your airfare costs?