Buying airline tickets can feel like a bit of a gamble. Even if you know how to play the game, there’s an element of chance involved — and there’s always a feeling of uncertainty when you go to book. Are you snagging the best airline deals around or will you find out later that you could have saved a couple hundred dollars just by waiting a week? While there isn’t always a definitive way to know for sure whether a price will drop or increase, the following points will help you avoid paying too much for your airline flights.

You’re Probably Overpaying for Airline Flights If…

…You’re buying outside of the “prime booking window”
While there are rare exceptions to this rule, the timing of when you buy your tickets, matters.

If you try to book a flight 2 weeks before you leave or more than 6-7 months prior to departure, you’re probably going to end up paying more than necessary. It’s good to plan ahead (and spontaneous travel isn’t inherently bad) — but when traveling on a budget, make your bookings in advance. Of course, exactly how far in advance is subject to debate.

USA Today reported last year that you should book “anywhere from 3-6 months ahead, with at least 6-8 weeks as the minimum buffer for buying plane tickets before incremental price hikes commence.” However, LifeHacker’s Kristin Wong recommends booking 21 to 122 days before departure.

.…You aren’t comparing prices
The FAA’s most recent data shows that there are 5,000 aircraft in the sky at any given moment and that 2,587,000 passengers pass through U.S. airports every single day. Each one of these passengers paid a slightly different price to do so. Although it’s usually a good idea to grab a good deal while it’s available, you may not want to take the first available ticket you find, either. If you have the time to spare, start your price comparison quest in advance and set up flight price alerts. That way, you’ll know you’re getting a great deal because you’ve seen how high (or low) the prices can actually go.

…You’re picking popular times to fly
If you choose to fly on a Friday or want to take a vacation during peak season, you’re going to pay more to do so. It’s really that simple. You’d be amazed by how much you can save on your airline flights just by changing your travel dates to mid-week, picking a less popular destination, or traveling during the off-season. Even switching up your airports or the time of day you fly can make a significant difference. Remember that you’re going to end up paying for convenience and desirable dates. If you’re willing to be a little flexible, you could save a lot.

…You’re flying direct
This isn’t really a hard rule, as many discount airlines offer highly affordable direct flights. But generally speaking, a direct flight is going to cost more than a route with connecting flights. Again, you’re paying for convenience and desirability here. Everyone wants to board and disembark only once without dealing with the stress of running around an unfamiliar airport or the possibility of missing the next flight. But if you can spare the time and have enough wiggle room during your layover, you may find that an itinerary with connecting flights may be much more cost-effective.

Want to know for sure? Most flight comparison tools offer you the option to compare non-direct and direct routes. Depending on the carrier, that one difference could allow you to treat yourself to a fancy meal or two during your vacation.

Next time you’re about to book your upcoming airline flights, give this list a quick glance. If you’re attempting to buy airfare outside the prime booking window or want to fly during a popular travel time, you may want to move some things around. And always remember to compare flight prices before you hand over your credit card number! If you’re a true bargain hunter, there’s nothing worse than knowing — too late — that you could have saved money.