By far, the easiest way to get to most places you'll likely want to visit while you're here is by bus. They're clean, inexpensive, and convenient, and unlike the metro they have big windows to view the city as you go. If you plan to visit The Capitol Building, the National Mall, the Smithsonian Museums, Union Station, or Dupont Circle, there's a bus stop two blocks away on 17th and C St. NE), and the D6 Bus will take you to all of these places in 10-15 minutes.
Take the same bus back and it drops you off even closer at D St. and 15th, and you you're basically home. Really simple and effortless.
The WMATA website is super easy to navigate: you just put in your starting address (1615 Isherwood St. NE) and your final destination--and it maps out 2-3 alternatives for you.
The Trolley Tours is a fun and inexpensive way to view all the major sites in and around DC--and you can hop on it not far away at Union Station.
(https://www.trolleytours.com/washington-dc)
A one day pass is about $56 and allows you to get on and off all day. They also have multiple day passes, a tour of Arlington National Cemetery for about $20, and a "Monuments by Moonlight" tour for about $100.
The Capitol Bikeshare is convenient and a great way to explore DC. Their website describes how to go about it and has maps of all the places where you can pick-up or drop off your bike. There are two pick-up stations within 5 minues of the apartment.
If you want to explore with an electric jumpbike or electric scooter, then you can rent one of Uber's Jump rentals throughout the city--and whereever they were dropped off the previous nigth or earlier in the day.
The DC Streetcar runs all the way up H St (from Benning Rd to Union Station), and is quick way to head down to the Whole Foods and Giant supermarkets, which are closer to Union Statoin. And the best part--they're free!
A Washington.org site that has useful informatoin about how to get to and from the airports, taxi services, parking, and so on.
If your travel to DC is through National Airport--then you're in luck since it's a quick 15 minute Uber/taxi drive from the apartment, or about 30 minutes if you take the metro. If you travelled via BWI or Dulles, here's a couple of websites that give you the bus, train, metro, and taxi options:
1.From BWI: https://freetoursbyfoot.com/transportation-bwi-airport-washington-d-c/#marc
2. From Dulles Airport: https://www.flydulles.com/parking-transportation/dulles-airport-metrorail-station