Got extra luggage to check? You'll have to pay. American and Delta airlines charge $25 for the first checked bag and $35 for the second one. The airlines do make exceptions. They typically won't charge the most elite members of their frequent traveler clubs or for passengers who are traveling to certain international destinations.
Otherwise, take a carry-on bag instead of checking your luggage to avoid these travel fees.
If you do need to check a bag, be sure to pack light. Major airlines charge fees of up to $90 per bag for overweight luggage that weighs 51 to 70 pounds, and the prices increase for heavier bags.
Also, check with your airline to see if it gives a discount for online baggage checking. For example, US Airways charges $20 for the first checked bag that's ordered online, compared to $25 to check bags at the airport.