If you plan to go through a real estate agent it is best to contact several of them. Many landlords and tenants prefer to deal directly with each other, but of course language may be an issue. You can find a home through an estate agent or with the help of a relocation agency , but most people buy specialized magazines which list hundreds of properties. In Paris many of the buildings are quite old, which means that they may not have an elevator . If there is one, it is not uncommon that it is a tiny, rickety one, which might make you feel unsafe at first.
Most apartments also have a code number at the main entrance.
So it is not enough to know the address, but you also need to know the code in order to enter the building and ring the doorbell. These are people who look after the building, and their apartment is usually right next to the entrance of the building. Parking is a big problem in Paris, so it is a real plus if you have a place. If not, you should ask where the nearest public garage is located, and then include the monthly cost of that when comparing rental cost. Make sure that is very secure.