Also, if you are not familiar with the Washington DC Metro system - when you
look at the map to determine which Color Line to use and which stop to use to exit the train - let's say for example that you want to take the Blue Line - on the map, note the names of the stations that are the end of the Line; in this example it would be Largo-Town Center and Franconia-Springfield at the other end. Now, when you get to the train station and go through the turnstile, you will see posts with Station Names on them - the Station Names will be the Station that is the end of the Line and indicates in which direction the train will be going. So, again for this example, you see 2 sets of stairways leading down to the train platform. One stairway has a post that says Franconia-Springfield and the other stairway has a post that says Largo-Town Center. By knowing what exit station you want, you know which stairway to use. In many stations, they have sign-boards telling you how long you have to wait for the next train.
Now, go back and look at the Metro Map again. Note the Stations that have "Bullseye" circles. The Bullseye circle indicates that is a station where you can transfer to a different line (e.g. transfer from the Blue Line to the Red Line). The transfer is free and you don't have to go through another turnstile. Note, that at your entry station, money is not deducted at the entrance turnstile - rather, the money is deducted at your exit station turnstile. Also the amount of the fare is time dependent , and distance dependent. Maximum fares are for rush hour periods. If you or someone in your party is 65 or greater, they are eligible for a Senior Smart Card. Very worthwile to get as it saves 50% or more on the fare. For more info on this, chech the Metro website.
Have a great trip.
Richard