Hi Sybilla, 

If you are only here for 6 months I suggest you find an apartment for sub-lease or try to rent a room - the classifieds here is a good place to start.

Good luck

Take a look at the university link as well. i got my studio there:

http://www.unige.ch/dase/bulog/form/bourse.php#loue

Or also see if the foyers have some free place (they have studios or shared rooms, cheap and nice): http://www.geneve-tourisme.ch/?rubrique=0000000020

Bonne chance!!!

All of the above plus don't forget the flat sharing section of immostreet.ch, biggest real estate search engine in Switzerland:

http://www.easywg.ch/?l=1

Good luck, be patient but active!

Geneva welcome center is also a good place to start Sybilla :). But you have to be patient as Geneva is a pretty hard nut to crack when it comes to find a decent place..

http://www.cagi.ch/en/logement.php