At age 21 my own 6-month internship on Cap Hill was unpaid. I came from across the country and both sold my car and got a waitressing gig in the evenings and on weekends to support myself. I sublet my apartment back at school.
Was worth it as I got many job offers at the conclusion of the internship. I kept the waitressing gig for 2 more years to start to build some savings. But I also got my own basement apartment
I had looked in the paper (Post) the minute I got to DC and after several dead ends I found a spot in an Arlington group house. It was a bit tricky as I also brought my (small) dog with me. I shared the master bedroom with 2 other females (we had 3 single mattresses on the floor) and there was also another female and one male who had their own rooms. All done in 3 days. I stayed with a friend of a friend for those first 3 days.
So basically do whatevr the equivalent is of that these days.