All of the popular international rental car companies, including Avis (www.nationalcar.com) operate in Puerto Rico. You'll also find literally dozens of local rental car agencies through your resort's concierge.

If you're renting from one of the well-known rental car agencies, call the company's toll-free number before you leave home to reserve your vehicle. This is definitely recommended if you want a rental car for part or all of your vacation, especially if you're visiting during a peak tourist season. Between Christmas and New Year's especially, it's common for the rental agencies to have trouble meeting the demand for cars.

It's often cheaper to reserve your rental car in advance and then pick up your vehicle at the airport when you land. Another option, which can sometimes be more expensive, is to rent a car from a branch office for a rental car company located at your resort (or one nearby). The cheapest option is almost always to visit one of the travel-related Web sites (such as Priceline.com, Hotwire.com, Travelocity.com, and Orbitz.com) to reserve your rental car.

To rent a car in Puerto Rico, drivers must be at least twenty-five years old and have a valid U.S. driver's license. While the roads are in excellent shape and navigating around Puerto Rico is relatively easy, keep in mind that virtually all of the road and traffic signs are in Spanish. Speed limit signs are also displayed in kilometers rather than miles per hour. Gasoline is also sold by the liter, not by the gallon.

If you're planning to rent a car in order to tour the island (a popular alternative to hiring a taxi or taking an organized bus tour), you'll discover that the roads are less congested in the middle of the week. (The exception is during morning and late-afternoon rush hours, as the local population heads to and from work or school.)