Bus/Tram and underground:

www.bvg.de
Underground station Naturkundemuseum (U6). From there it takes approximately five minutes to the Luisenstraße. 

Interurban train:

www.s-bahn-berlin.de

Interurban train station Friedrichstraße:

http://www.berliner-bahnhoefe.de/friedrichstrasse/lageplan.html 
Approximately fifteen minutes footway to the Charité or you can also take the bus 147 from the interurban train station Friedrichstraße to the stop Charité Luisenstraße.

Central Omnibus station:

www.berlinlinienbus.de