Don’t forget online travel agencies (OTAs)
It may be cheaper to fly out on one airline and back on another using one-way fares, and OTAs such as Expedia and Priceline are a good place to find out. They also sell air plus hotel packages that usually cost less than buying separately and they sometimes have fares that are much lower than the same flights and dates sold directly by the airline sites (I recently saw fares on Priceline to South Africa on Dutch airline KLM that were hundreds less than if bought on KLM.com and fares on Delta to Italy that were much cheaper on Expedia than on Delta.com).
Make sure the site covers Delta
And speaking of Delta, that airline restricts where its airfare data appear on some popular third-party sites such as Hopper, Hipmunk, TripAdvisor and FareCompare.com so beware. JetBlue recently removed its fare data from several “meta search” sites as well.
Choose “basic economy” fares with care
Copying ultra-low-cost airlines such as Spirit and Frontier, now Delta, American and United also sell bare-bones economy class fares. On domestic routes, they typically cost $40-$60 round-trip less than regular economy, although the savings can be greater to international destinations. Buy one of these fares and, except on Delta, you’ll pay even for a carry-on bag unless it’s small enough to fit under the seat in front of you; you won’t be able to choose a specific seat before check-in (which means you’ll end up in a dreaded middle seat), and your fare will be entirely non-refundable and non-changeable. Although I’d never buy one of these airfares, my millennial friends, who apparently travel with just a change of clothes and a toothbrush stuffed into a backpack that slides under the seat, tell me that they’re worth the inconvenience.