MainStreet Explains: How Much Extra Cash You Now Need to Fly

American Airlines (AMR) will soon charge us an additional $30 for checking a bag on a round-trip flight. Why not just raise its fares as fuel prices rise and spare us a more cramped cabin?

Because--let's face it--a good chunk of us go online, find the lowest fare on a flight aggregator like Orbitz (OWW) or Expedia (EXPE), and buy our ticket. Forget the airline's record with most on-time flights. Who cares if there's in-flight entertainment? We see a flight from Milwaukee to New York for $69, we're buying it.

For airlines, fees are a way to game the system. Sure, one airline may charge $69 for its base fare, but tack on baggage fees, reservation fees and the cost of peanuts. Soon, you may be paying more than you would for a flight that, at first glance, looks more expensive.

So how do you avoid being taken? Here's a rundown of questions to answer before you assume the ticket with the lowest fare is going to end up costing you the least. Fees apply to domestic flights, and many can be avoided if you belong to an elite travel club, pay full fare or buy unrestricted tickets.

But for those of us looking for a deal, here's a rundown of how to get the best deal.

How much is the first bag going to cost me?

Alright, so only American Airlines has announced plans to charge for the first bag of stowed luggage. But after June 15, it'll cost most of us an additional $30 if the bag's traveling round-trip. If you're thinking, "I'll just pack my one carry-on bag extra tight," remember, everyone else is thinking the same thing. Even if you can cram all your stuff into the one bag, you might want to consider shelling out a few extra bucks for a flight where each passenger isn't desperately trying to carry as much on board as possible.