Looking for a flat/room for at least 6 months

I'm a portuguese student, with 23 years, non smoker, moving to Darmstadt to study in TU. I'm taking a master degree in Advanced Materials Innovative Recycling (related with Materials Science).
I'm looking for a place to live during the next semester (possibly the following semester as well).
I would like to find a nice and cozy place, furnished and with a kitchen. Preferably it should be a 1-room apartment, but it can also be a room in a shared place (apartment or house). A balcony or terrace would also be nice, but it is not mandatory.