Apartment hunting in Paris can be quite challenging !!!! Be prepared ...
First and foremost get on social media. If you have a fellow citizen from your home country in Paris, start there.
Several online platforms exist to find an appartement:
These two are real estate agencies. Most of the time there is a fee to be paid to the agency once at the beginning of the rental (generally equal to 70-100% of the monthly rent).
There is a limit for agency fees. In the case in Villejuif, when I asked for an apparment I learned that agencies can not ask for an amount of fees higher than 15euros per square metre. For instance, for an appartement of 40 square metres, the agencies fees must be less than 600 euros.
Other platforms exist between individuals (you don't pass by an agency)
There is a security deposit to be paid. It is restituted at the end of the renting period if no damage were done to the appartment. In general, it is equal to one month rent if the apartment is not furnished, and two months rent if it is furnished.
Generally rental contracts are for one year and can be easily renewed if both parties agree.
You can leave the apartment anytime, you need to give a one month notice before.