There are quite a few helpful resources for learning French in DC.
The most obvious is the Alliance française, which gives French Grammar and/or Conversation classes, but also has a library with French books, and organizes events for the francophile community. A lesser known resource is the International Club of DC. They regularly organize “languages of the world” evenings, including French conversation. Event schedule updates are sent regularly through a subscription to their Newsletter.
Finally, the Maison Française also organizes events around French culture, including movie nights and scientific seminars.
All those events are great opportunities to meet French speakers, which is ultimately the best way to practise and improve your language skills :-)