The best way to get to campus is to arrive at 3700 O Street NW, Washington, D.C. 20057. This is the front gates of the university.
Darnall Hall - Dormitory
Map of Georgetown University
For parking at the university, information can be found at http://otm.georgetown.edu/index.cfm?fuse=parking. Nights and weekends are free.
Street parking around campus is severely limited and strictly enforced by the DC police (MPD) and the DC Department of Public Works (DPW). Most streets require a Zone 2 residential permit issued by the District of Columbia for parking for longer than two hours. A limited number of metered spaces are available on Reservoir Road, 37th Street and Prospect Street.
For parking in the surrounding Georgetown area, check out http://dc.about.com/od/transportation/a/GeorgetownPkg.htm
For buses, your best bet is with the G2 or D6: http://wmata.com/pdfs/bus/DC.pdf
If you are taking Metro Rail, your best bets are Rosslyn or Dupont: http://wmata.com/index.cfm From Dupont, you can take the G2 (runs on weekends) or GUTS. From Rosslyn, you can take a short taxi ride (5-10 minutes), walk (15 minutes) or GUTS (5-10 minutes).
Georgetown University Transportation Shuttle (GUTS): http://otm.georgetown.edu/guts/index.cfm (will not be running on the weekends)