Coming from Munich, follow blue signposting "A 95 Garmisch-Partenkirchen". Leave motorway at exit Starnberg. Once in Starnberg, at the second traffic light, turn right into Moosstraße. After approx. 50 m you will find number 3 on the left hand side.
With public transport S-Bahn (Duration: 1,5 h):
From the airport you can take either S 8 or S 1. Change train in Laim into S 6 direction Starnberg / Tutzing which leaves normaly platform 1.
If you are in S 8 you can stay at the same platform you arrive and wait for S 6. If you are in S 1 you have to change to the platform in opposite the one you arrive.
From the mainstation take S 6 direction Starnberg / Tutzing which leaves underground.
For more information about the S-Bahn (timetable, prices) see http://www.mvv-muenchen.de