● Choosing a Rental Car Company
Before you even consider which company to go with, you are going to want to evaluate your needs, decide on the size of car you want so that you can avoid making hasty or expensive decisions. How long will you be renting? If it's for less than a week, you'll probably do best with a major company, for rentals of a week or longer, you may get better rates from local companies, particularly auto dealers. Make sure ask about special deals, discounts and credit card programs you may belong to. They'll frequently offer deals on car rentals. If you're employed by a company that frequently rents cars, they may have a negotiated rate. Make sure to check. Always shop around, even on the Web. Many companies often offer Web-only discounts, take advantage of them whenever possible. Make sure to ask if there will be extra charges that will increase the base rental rate: fuel charges; mileage fees; additional-driver fees

● Drivers License
All car rental companies require a valid driver’s license.
In some foreign countries, an international driver’s license may be required.

● Driver's History
Some car rental companies check the driver's history and will deny a car to a customer with a poor driving record. Ask if the rental car company checks the driving records of customers. Some companies will reject customers whose driving records don't meet company standards. Even if you have a confirmed reservation, you may be disqualified from renting a car for violations within the last few years, including accidents, seat belt law violations, regardless of fault, convictions for Driving While Intoxicated (DWI), Driving Under the Influence (DUI), reckless driving, or leaving the scene of an accident, or driving with an invalid, revoked or suspended  license. Ask your rental car company in advance, whether your driving record will be checked.

● Age Restrictions
You will encounter an age limit at every car rental company. Most agencies will have a non-negotiable minimum age requirement of 25. For consumers under 25, a credit card is usually required for payment and the rental rate may be slightly higher. The "younger driver" surcharge varies from agency to agency, and even location. Even if you do meet the age requirement, some agencies have an upper age requirement for certain vehicles (e.g. you must be at least 30 years old to rent an Audi TT from Hertz). On the other end of the age spectrum, some companies may decide not to rent to senior citizens. If you are government or military personnel, you may be exempt from the age limit. However, the rental vehicle must be used for business purposes. A similar exemption may apply if you are a corporate employee who has an agreement with the rental company, and are using the rental car for business purposes. Check with the agency to get clear details about the younger driver policy and your particular situation. The easiest thing is to check the company's policy beforehand; call the hotline or check the website.

● Additional Drivers
Read the rental contract carefully; it will specify who can drive the car. If you are going to need or want other people to drive your auto rental, it is necessary that you inform the rental company. Signatures of all drivers and their driver’s licenses may be required to rent the car. There may an extra fee for each additional driver. If you do not have any other names stated on the rental contract, it is prudent not to let anyone else drive the rental car. Allowing some unlisted person to drive your rental car may even void personal insurance or any insurance provided by your credit card. This could result in serious consequences if the car has been in an accident. In an extreme case, however, the unlisted person driving the rental car could be charged with theft, if caught by the police.

● Credit Card
Most big companies do not accept cash deposits as payment. They require a credit card to guarantee. And you can be denied a car rental if you have a less than almost perfect credit history. Besides what if you can't pay for the car? The company needs a guarantee for services. If a credit card is being used for payment, be aware of your credit card limit; some car rental companies require immediate credit approval before renting  car which can substantially reduce your remaining balance of credit. Many car rental companies will accept their own pre-paid vouchers issued by an appointed travel agent. Some car rentals require that you fill out a cash qualification questionnaire at the rental location. The final acceptance of a non-credit card rental, however, is the decision of each individual rental location.