Forget mailing bags ahead of time. "It's going to cost you more to ship your luggage," than it would cost you to check the bag, says Lytle.
Also, board as early as you can. Since everyone is switching to carry-ons, those overhead bins are filling up fast. Keep an eye on your luggage, even after you stow it. With a shortage of available space, incoming passengers have been known to "rearrange" the existing luggage to make room for their own.
6. Change fees. Need to change your schedule? Expect to pay an extra $150 for domestic flights, up about 50 percent from last year, says Seaney.
"To me, that's the one I dislike most," he says. "They are already charging you the difference in price for the new ticket," he says. Because it's usually booked at the last minute, it's already going to be a higher rate.
Avoid by: Other than trying to sweet talk a ticket agent, there's really no way around this one.
7. Phone reservations. Want to talk to a human being when you book that reservation? That's an extra $15 to $30 per ticket with some airlines, says Seaney.
There's less overhead for the airline (which means more profit), if you book through their Web site. So they're trying to give you a financial incentive to use the online service.
"The bottom line is they're trying to prevent people from talking to humans," says Seaney. And 60 percent of flyers do book online.
Avoid by: Doing the phone line/online two-step. Just about every traveler has questions before booking airfare. So call the toll-free numbers and nail down all the details. (While you're at it, ask what the charge is to book by phone).
Once you've done that and know exactly which route, flight and seat you want, then hang up the phone and book online. While it makes zero sense (the airline still has to pay the salary of the phone agent), at least you'll likely save a nice chunk of change for exactly the same accommodations.
8. Pet fees/unaccompanied minor fees. Both of these have gone up substantially on many airlines. Some have even doubled in the past year. Best bet: if you have kids or pets traveling alone over the next few months, ask about fees so that you know what to expect.
Avoid by: Streamlining the itinerary. Fees for unaccompanied travelers (either two-legged or four-legged), often increase exponentially if there are stops or plane changes. (The quoted fees are usually for each leg of the trip, so adding a stop can double the fee.) A nonstop route will usually minimize fees, but you want to balance that with the needs of the traveler.
Join and save
There's one more way that you can eliminate a lot of the airlines' add-on fees: join a frequent flier club. "In many cases, fees won't apply to upper tier frequent fliers," says David Castelveter, vice president of communications for the Air Transport Association, a trade group for the major U.S. passenger and cargo airlines.
Not spending enough time in airports to qualify? You might be able to get in by using an airline-affiliated credit card to collect frequent flier miles, Seaney says. "That can give you elite status," he says.
If you're already a member of another carrier's frequent flier program, simply request membership with any other airline you're planning to fly. Competing airlines love the opportunity to win your business, so they'll automatically enroll you for a year, says Seaney.
The bottom line for all fliers: get educated and keep asking questions.
The fee system is "byzantine," says Lytle. "Just when you think you've figured it out, they will change it or add something different."
Never assume the rules are the same as the last time you flew. Each time you travel, be persistent in asking about any fees or add-ons.
When cost is an issue, Seaney says, "You can get around most fees if you use some common sense."