Find the "RER" signs from the airport. Taking the RER from either Charles de Gaulle or Orly airport is a far less expensive option than taking a taxi into the city center, and both trains into the city are about equal time. RER trains are part of the Paris metro system, and signs at the exits of both airports show the way to the RER.
Obtain a brochure with the "Métro Parisien" map. This is a useful map of the Paris metro system, found either on its own or as part of the "Plan de Paris" brochure. It offers useful information about the bus lines and metro stops that serve main tourist destinations in Paris. These maps are offered all over RER stations and airports.
At the RER station, buy your ticket into the city. Heading inward will not require an additional ticket when changing to a different metro line (this is always true in Paris: tickets may be used for multiple stops inward or outward, and new tickets are only required if a passenger exits the metro station to the street). At the RER window, show the service person the address of your destination, and he or she will point out which metro line and stop to take following the RER.
Change metro lines. When the RER reaches your metro stop in the city, you will likely exit and question whether to go left or right. The signs on the wall reveal the metro lines by number and color. Follow the signs to that line. For example, if you change to the 5 metro to Gare du Nord (maybe the busiest stop in Paris, offering access to most metro lines), two directions will fork off: one labeled "Bobigny-Pablo Picasso" and the other labeled "Place d'Italie." These are the last stops on either end of that line, and indicate the direction the train is going. Look on your metro map to see which direction you are heading, and follow the appropriate sign.
Buy additional tickets. Once you've reached your hotel or other destination, you will need to obtain more tickets for travel throughout Paris. Purchase tickets at the machines in the metro stations, with the option to buy multiple tickets at once.
Reference the metro map for sightseeing destinations. Many Paris attractions are on the metro line, including the Champs-Elysees, the Bastille, La Fayette and so on. While buses are widely available and service most areas with the same ticket cost, the metro line is fast and easy, and often saves time.
Make use of the bikes! Paris now has a public bike system, offering thousands of bicycles at hundreds of stops all over the city. For a small fee, travelers can get on a bicycle and drop it off at any of the other bike locations anywhere in the city.
