We had the option to drive down to DC but we didn't; we took a bus. We didn't want to deal with the actual trip down (I like sleeping), we didn't want to deal with fueling up, and we didn't want to deal with parking. Even if we had driven down to DC, we wouldn't have driven around the city anyway. Why deal with trying to find a parking spot or meters or fees for lots when there's an amazing public transportation system and Uber?
Let's discuss the Metro first. The DC Metro has five lines (red, blue, orange, yellow, and green) and has a sixth line that's currently under construction (silver). The lines wing out like an asterisk to different parts of town and into Virginia and Maryland.
Most frequent Metro riders have the SmarTrip card, which is a permanent and reloadable card that can also be used on buses. But, if you're only in DC for a trip, you'll probably just pick up a paper Metro card. You can get a paper Metro card from one of the machines in the station and add money to it, as necessary. If you're planning on taking the Metro just once, you can put in the exact amount you need or just throw a few bucks on and wing it. You'll have to feed your card into the machine when you enter the Metro and again when you leave so don't lose it! If you happened to not put enough money on your card for your ride, the turnstile won't let you leave but don't worry. You can go to one of the machines and throw some more money on the card.
The paper Metro cards don't work on buses. For buses, make sure to have some cash (small bills!) on you. Each regular ride is $1.80 so have some coins as well, if you care about the $0.20 loss. Each express bus ride is $3.65. Just feed the money into the little money machine; and remember, you don't get change back so have exact change with you. Tip: for bus rides, just use your Google Maps app on your phone to help you figure out which bus to take.
Anyway, back to the Metro. Once you make it underground, you'll have to decide which train to take. Each line runs in two directions (duh) and the direction is indicated by the final stop on each end. So, for example, if you're taking the green line, you'll either be heading towards Greenbelt or Branch Ave. If you're unsure of which direction you need to go, just look around for a map or one of the columns that list the stations that each train is heading to. Once you figure out where you're going, wait on the appropriate side. When a train is approaching, the little lights along the edge of the platform will start to blink. Hop on the train, listen and watch for your stop, and get off when you're supposed to. Feed your card into the turnstile when you're leaving and you're good to go. By the way, your paper card will have its new balance printed onto it when you leave.
So that's it for my take on getting around DC. If you have any tips of your own, throw them in the comments!