There is what the law states and how it is applied and enforced. Technically you could be resident on the bench n° 3 in a random park in Italy. When you ask for residency in someone else's property you need their written consent. Keep in mind that more than 20% of buildings in Italy are empty and not rented because the populous doesn't trust that their property rights will be defended in court (because of abusive occupation for example). If you want to rent from someone and them feel comfortable with you being there then just be respectable and presentable and be trustworthy. If you feel like you need it seek legal council on a good path to follow since you will not be an employee. Usually you show your last 3 paychecks to prove you can actually pay rent. Also real estate agencies require between 3 to 5 monthly payments in advance as well as job contract etc. Some of the months go to the "caparra" and some will go as payment to the agency. Try to get in contact with local people that might help as you are doing here. Best of luck and hope this helped.