Spanish boy looking for a room or studio to rent in Berlin

My name is Borja and I am 33 years old. I work as a university lecturer in Spain. I am going to do a 3-month research stay at the Freie Universität Berlin from 15th April to 17th July. I like reading, watching films and series, and walking. I am a very organised and responsible person. I love animals and I do not smoke. I speak English. I am also a quiet person who avoids disturbing others. I'm looking for a room to rent close to Dahlem (Steglitz, Wilmersdof, Charlottenburg, Zehlenhof, although I would be interested in other areas with good connections regarding means of transport).