I had been chatting with the woman next to me during a recent flight to Baltimore when the subject turned to airfares.

The woman, on vacation to visit family, revealed she had paid nearly $300 for her ticket.

“How much did they get you for?” she asked, assuming I’d shelled out a fortune as well.

She looked aghast when I replied: “About $138,” noting that I’d also recently scored another ticket to Washington, D.C., for the same price.

Needless to say, the woman didn’t speak much during the rest of the flight.

Call it airfare envy.

On any given flight, travelers pay wildly different fares for the same seats. Nothing stings more for a budget-conscious traveler than learning other passengers paid hundreds of dollars less for a ticket.

So how do you turn up that elusive low fare? It’s all about using the Internet.

Here is a list of the methods, resources and Web sites I use for finding cheap tickets online.

A few caveats: There are times when you’re forced to pay more than you want to, especially on peak travel days or on routes where there’s little competition. There also are plenty of other ways to find cheap tickets – such as through consolidators and bidding sites. So this isn’t comprehensive, by any means.

Finally, you must consider other costs. If you stay an extra day in New York City to save $100 on airfare yet shell out $200 for another hotel night, it’s probably not worth it.

But here’s how you can, more often than not, score a cheaper seat using options on the Web.

Put in the work: Finding a great fare isn’t always easy, especially as carriers hike prices to offset rising fuel costs. There isn’t a magical Web site or a special phone number or a supersecret airfare newsletter.

Yes, you can stumble onto a great fare. But getting one on a regular basis takes time. It usually includes several hours researching fares on the Internet, spread out over a period of weeks or months.

But in many cases, it’s worth the effort because you can save hundreds of dollars a year on airline tickets.

Be flexible: This is the hands-down, No. 1 rule to finding cheaper airfares. It applies to every part of the process, from the airline to the destination to the time of day to the day of the week you travel.

Most sites have added features in recent years that make it easy to compare options, such as using secondary airports.

If you can leave a day earlier or return a day later than initially planned, you can significantly cut your fare. Ditto, if you can fly really early in the morning or late at night.

Don’t start planning the exact dates of your trip until after you at least glance at ticket prices. Too many people decide which days they want to travel and then start looking for fares. By that time, they aren’t willing to budge.

Use multiple searches: Some Web sites let you search for the lowest fares on a particular route over a few weeks or months. Others also let you check out fares for a few days surrounding the dates you want to travel. You don’t have to book through those sites, but you can use the information to plan your trip.

Mondays, Tuesdays and Wednesdays are the best times to travel, as demand is lower. If you must travel over a weekend, try to tweak your plans. I typically find cheaper weekend fares for flights leaving Friday morning and returning early Monday morning, rather than, say, Thursday night through Sunday.

Flexible fare search helped me save big last year on a trip to Italy. I found a fare for about $520 leaving March 31. If I had left just one day later – in April – it would’ve cost nearly $200 more.

Don’t assume the ‘Big 3’ have the same fares: Yes, fares listed on Orbitz, Travelocity and Expedia often vary by only a few dollars.

But don’t discount checking out all three, and numerous other sites, too. I recently found a $200 fare to San Francisco on Expedia, even though all the other sites listed it for $260 or higher.

Subscribe to e-mail updates, other alerts: There’s an abundance of fare newsletters, offered by all of the major booking engines, every airline and other sites such as TravelZoo.

Many alert you via e-mail to deals from your preferred departure city or on specific routes that you choose. Frontier Airlines and Southwest Airlines provide updates for sales that expire in just hours. United’s updates sometimes have great last-minute fares to Asia and Australia.

One-way vs. round-trip: Sometimes it’s much cheaper to fly, say, United to Las Vegas and Frontier back. Kayak is great at matching up one-way flights for round-trip travel. But you can also find even better deals on your own, especially if you look for one-way fares using Southwest Airlines and another carrier (Southwest’s fares aren’t listed on third-party sites).

Don’t forget airline sites: Once you find the best days to travel, try a few airline sites, as they will be your best bet for cheaper fares.

Third-party sites typically add $5 to $10 service fees. And some airlines such as Frontier guarantee that their sites will always have the lowest prices.

Fly international low-cost carriers: You can save a bundle by flying a major airline into, say, London, and then taking a low-cost carrier such as EasyJet or RyanAir to your destination. There are numerous low-cost carriers in Europe, Asia and elsewhere. Many have English Web sites, and booking is usually a snap.

Consider flying to and from multiple cities: Most airline and booking sites include a “multicity” search function you can use to arrive at one destination and return from another. This works especially well on international flights.