Fee for all: avoid airline surcharges before you take off.

You've heard the expression "What you don't know won't hurt you." Well, that doesn't fare well when it comes to your money. Hidden charges can take a toll on your wallet. While hotels, car rentals, and vacation getaways are notorious for having surcharges, travelers should be particularly aware of hidden airline fees. You are probably already familiar with the feet that most major airlines charge for last minute flight changes. However, most have also implemented fees for in-flight meals and movies, and international taxes.

You can avoid unforeseen fees by keeping these travel tips in mind when buying your next plane ticket:

Change of plans. If you have a sudden change of plans, cancel your reservation as soon as possible. Penalties are less the earlier you cancel. Most major airlines charge up to $100 to change your itinerary before you take flight.

Paper vs. electronic tickets. Paper tickets are often an additional cost. Expect to pay $20 to $50 more when there is an eligible electronic ticket itinerary. Some airlines have discontinued the use of paper tickets altogether. However, it is necessary to use a paper ticket for international travel. (Foreign countries often require evidence of return travel.) For this reason, Continental offers paper tickets only for international flights.

Ticketing fees. Plan on buying your ticket according to which method has the least fees. For instance, Continental charges $5 for booking a ticket via a telephone reservation center and $10 via an airport ticket counter. American charges $10 for tickets purchased at their travel centers and airport ticket offices and $5 at reservation offices.

Baggage. Airlines have a free baggage allowance, which includes two checked bags, one carry-on, and one personal item such as a handbag, laptop, or stroller. There are three different types of baggage fees: excess, overweight, and oversize. To avoid overweight and oversize fees, baggage should weigh less than 50 pounds and be fewer than 62 inches. Overweight fees are commonly $25 if your bag is less than 70 pounds and $50 if it is less than 100 pounds, while oversize fees are usually $80 at most airlines. Bags weighing more than 100 pounds or those longer than 80 inches might not be accepted at all.

Minors. Unaccompanied minor fees are approximately $40 for nonstop flights and $75 for connecting flights, per direction. The definition of minor varies by airline, but in general, a child is considered to be between ages 5 and 14. American, United, and U.S. Airways prohibit children ages 5 to 7 from having connecting flights. International flights incur additional fees.

Standby. These fees pertain to upgrades only. A few national airlines have standby fees. Delta's fees vary from $50 to $150 depending on mileage. U.S. Airways has a flat fee of $25.

Since charges vary, it's important that you contact your particular airline.