If you've looked into the requirements for your permesso di soggiorno once you arrive in Italy, you see that one of the requirements is to have a rental agreement for a home in Italy. (You can also have a receipt for a hotel or hostel stay of at least 30 days.)
This can be stressful to figure out when you're still living in your home country! Here I've got a few tips to help you.
Look at a Short-Term Rental
As I've learned, it's tough to get a sense of a town enough to know you'll want to live there for a year or more when you just visit for a few days. And note: some towns primarily offer rentals for multiple years, so it's a lot of pressure to sign a rental contract for three or more years when you don't know if you're going to love the town or not.
An alternative is to find a short-term rental. Airbnb is an obvious choice, but also check Facebook groups for the town you're considering, because you might find a place for cheaper. Make sure, though, that the owner is willing to write you a contract because this piece of paper is very important in helping you get your permesso di soggiorno! A lot of Italians (I've found) don't want to create a contract because they have to register it with the tax agency and pay taxes on it.
Ask Around
As you start to build your community in Italy, ask anyone and everyone if they know of a place you can rent.
I was told that it was impossible to find a year-round rental in Soverato because people leave their apartments empty all year and then make a lot of money in the summer months. But I didn't want to live somewhere for nine months and then have to move (with two cats) for the summer.
So I asked everyone I knew. And lo and behold, a neighbor knew a guy willing to rent to me. Yes, I will pay more for the summer, but I got the contract I needed.
Accept the Italian Way of Doing Things
As I said, Italians don't like creating contracts because they have to pay taxes on them. You might encounter a situation where your landlord wants to put a lower monthly rent on the contract so he or she can pay less in taxes.
I resigned myself to this "gray area" since it doesn't hurt me in any way and enables me to get the contract I need.
Rent a House in Italy Before You Buy
I wrote about this recently, but I just want to reiterate that it's a better idea to rent a house or apartment in Italy before deciding to buy. It gives you time to get to know the area, as well as what's a good price (and what's a ripoff because you're foreign).
One final tip: when you rent a house in Italy, use Google Translate to scan the contract so you can read it in English. If you have questions, consult a commercialista about the fine print.