In the past, you could count on Tuesdays as the best day to book a great flight deal. Skyscanner data from millions of flight bookings in the last year show the overall best time to book flights from the U.S. is on average 23 weeks before departure." Try a few different options, because sometimes just moving your flight by a day can save you quite a bit." “Instead of booking one round-trip ticket, book two one-way tickets or separate legs on different airlines," he explained. Sometimes, you just have to book that ticket no matter the cost.