As most seasoned travelers know, airfares are never guaranteed. On any given day, prices can go up or down without notice, but these tips will help you snag the low fares that are so difficult to come by these days.

1.   Check fares early and often

Airlines change their fares multiple times a week. The difference between the best day to buy and worst is $1,500 to $3,000 on international Business Class flights and $300 on average for domestic economy flights, according to a study by CookTravel.net.

2.   Buy when the time is right.

On average, 49 days in advance was the optimal time to buy a domestic ticket, according to a study by CheapAir.com. But since this can vary depending on travel dates, demand and destination, the safest bet is to not book too early (more than five months in advance) or too late (less than 14 days in advance). For international Business Class trips, it’s best to book 11 months in advance, but these tickets are non-refundable.

3.    Be mindful of seasonality and holidays.

The most important factor that influences the price of a flight is how full it is. Traveling during spring break, Thanksgiving or Christmas is cheaper for Business and First Class but more expensive for economy class.

“It’s crazy. First and Business Class fares are completely opposite of Economy fares,” said Katrina Roberts of CookTravel.net. “When Economy prices go up, Business and First Class go down. And vice versa.”

The same holds true for certain destinations. Passengers can snag great deals to Europe during January, February and March, but prices can double during the summer.

If you need to travel during high seasonality, book early. Discount seats are likely to sell out quickly.

4. Some days are cheaper than others.

Business Class seats are less full on Saturdays, meaning they’re less expensive as well. It’s generally cheapest to fly Coach on Tuesdays and Wednesdays and more expensive to fly on Fridays and Sundays.

5. Know when to use your miles.

Ask yourself if it’s worth spending frequent flier miles to pay for the fare. But, rather than cashing in 25,000 to 50,000 miles for a domestic economy seat that costs $250 to $300, splurge on a trip to Europe instead, where the fare would cost two to three time more (50,000 will do the trick on some airlines). Or consider upgrading your $400 domestic economy class seat to a $2,800 Business Class seat for 30,000 miles

6. Check alternate airports.

The more options you have, the more discount seats you’ll have to choose from.

7. Benefit from using a travel agent.

You’d be surprised on how much money, time and frustration you’ll save while using a travel agent.Many have access to net fares, consolidator fares, and vacation packages that much cheaper than if than the sum of individual rates.

Ask your agent about upgrades. Some have access to corporate fares.

Also, when international itineraries get complicated and travel emergencies arise, knowledgeable agents are available to help. Some don’t even charge any fees for their services.