As far as I know, most car rental companies are located near airports or in the heart of the city, not in highways or countryside, therefore is pretty likely you are going to find well paved ways instead of neglected dangerous roads. You can make reservations over the phone or internet, and ask all the questions you wish to customer support. I guess they would ask for your current license or whether you have a credit card or not. Even some of them just have an age requirement instead, like some US companies which only lend a car for customers older than 25 years old. Is a good idea to contract a car insurace before thinking in car rental, remember that every serious company will make you responsible for any damage or loss of the vehicle while you are renting the car.