The national driver's license is accepted in several countries, but in most cases you need to have a minimum age to rent a car and the international Driving Permit (PID).
It is best to consult the consulate of the country you wish to visit and verify the need for the issuance of the document and any other type of requirement. United States, England and Canada are some examples of countries that accept international permission.
At the time of rent, check the car, safe and additional options (GPS, Baby seat, among others). Choose the most fit with your needs and especially with your budget.
Before you leave with the car, take a survey of the vehicle. Check the operation of the arrows, the car lights and brakes. Report any problem to the responsible employee.
Another important care you must have is with the traffic laws of the country you intend to visit. In England, for example, the steering wheel is to the right of the car and the circulation system is made by the left. Stay tuned!
Drive carefully and always respecting the country's traffic laws. And if you drink, don't drive!