First, cheaper dates for U.S. domestic fares:

•May 20: Call this the last date to fly for the cheaper spring season. Prices are not as cheap as winter fares but there are a lot of bargains; advertised deals are from $39 one-way, even on larger airlines like Southwest.

•June 14: This is the last day for cheaper pre-summer fares because starting June 15, the peak season begins in earnest. The entire trip doesn't have to be in early June; just be sure to take off by June 14.

•Aug. 30: This is the start of the bargain fall season; it starts a little later than usual, but there’s still time to get a nice trip in before Labor Day (Sept. 4). If this looks good, wait till the next wave of price-drops in late October, another great time to save.

Now cheaper dates for transatlantic routes to Europe.

•May 11: If London, Paris or Rome are on the agenda, try to squeeze in the trip before the price hike of May 12.

(Can’t fly then? Don’t worry; there are still some excellent fares to Europe even in July: New York-London, $595; Los Angeles-Paris, $706; Boston-Copenhagen, $392 (no kidding). These prices were found late last week on the site.)

•Aug. 30: This is just like the domestic fare drop-off; the fall season for Europe begins and prices go down. Traveling this time of year has other benefits, too, like cooler temperatures and fewer crowds.

Other ways to save besides booking the fly-dates.

•Fly cheapest days: Domestically, these are usually Tuesdays, Wednesdays and Saturdays, and cheaper days for Europe are often midweek. Flying at least one leg of a trip on a cheaper day will still save something.

•Fly hub-to-hub: It can pay off to fly to-and-from big airports, even if they’re not the closest ones. Check fares for both; if the trip is long enough, the savings could make that long, inconvenient drive to a bigger airport worth it.