Who doesn’t want to find a cheap flight for their next trip? One of our favorite tips for scouting great airfare is to watch the sales. All of the major airlines offer discounts and promotions from time to time, particularly when destinations go into their off-season. To be privy to these, all you need to do is sign up for your preferred airline’s email list. They’ll send them straight to your inbox.

Another way to use these sales, however, is less obvious -- and is especially helpful if you like to fly on one specific airline. Here’s how to do it: Say, for example, that you’re looking for a low-priced ticket to Europe in spring. Any time you see an airfare sale to Europe -- even if it’s not on your preferred airline -- you should do a quick fare check on your preferred airline’s site. Many airlines drop prices when their competitors offer a sale. This helps them compete and keep your business when there are great fares elsewhere in the market.

For example, Delta and Emirates are in neck-and-neck competition on the route between New York City and Milan, Italy. When one offers a sale on these flights, the other often matches the fare. This has meant incredibly affordable flights between these cities -- as low as $399 roundtrip in low season. Keep your eyes peeled, and you can take advantage.

As with all airfare sales, though, keep one thing in mind: You'll need to move quickly. If you wait hours or even days, those great prices likely won't be available when you check back. For better or worse, airfare may be the one place where impulse shopping actually pays off. (It helps, too, if you run through this checklist for taking advantage of limited-time deals.)