To get the best deal, book through a travel agent who is willing to shop around. When pricing cars, ask about the location of the rental lot. Some off-airport locations offer lower rates, and their lots are only minutes from the terminal via complimentary shuttle. Remember to ask about required deposits, cancellation penalties, and drop-off charges if you're planning to pick up the car in one city and leave it in another. Be sure to look into wholesalers, companies that do not own fleets but rent in bulk from those that do and often offer better rates than traditional car-rental operations.
Prices are best during off-peak periods.
Rentals booked through wholesalers must often be paid for before you leave on your trip. Some rental agencies charge extra if you return the car before the time specified in your contract, so ask about this in advance. To avoid a hefty refueling fee, fill the tank just before you turn in the car, but be aware that gas stations near the rental outlet may overcharge. And any gas that is left in the car is, in fact, yours, so don't pay for something you aren't going to use. When driving a rented car you are generally responsible for any damage to or loss of the vehicle.