Looking for a studio or a room in a shared flat in Berlin

My name is Ruben, I am 26 years old and I am from Spain. I am moving to Berlin in November because of a three-month internship (from November 1st to January 31th). I am looking for a studio or a room in a flat between 250-500/600 approx. (preferably expenses included).

I've been living in so many places lately (The Netherlands, Madrid, Barcelona...), so I have experience sharing flats and living by myself. If the place is between the quantities mentioned above, there will not be any money issue, so I assure any landlord that accepts me in his/her flat that payments will be completed on time. All I want is to have a pleasant stay in Berlin. I am an easy-going guy, clean, nice and very quiet. Not looking for problems or issues, just something easy and kind from both parts.

PD: It might happen that my stay can be a bit longer, but I will not know it until January.

I appreciate the time of the people who read this.

Thanks in advance,

Rubén