Before You Go
Getting here is a lot harder than most would expect. If you are an American, Canadian or Australian, you do not have the right to work or live in Italy. Because of this you need to find ways to work around the obstacles that governments and history have put up.
When I say getting around obstacles, understand that I mean in a totally legal sense. I am one of those obnoxious people who do things the legal route. Since there are ways to do things legally, there is no reason to do things illegally. The cost is too great. Expulsion from Italy
One of the easiest ways to get here is to have citizenship from an EU country. With that, you have the right to live and work in Italy and your spouse and children have the right to follow you. You will still have to deal with paperwork and bureaucracy but you don't need to get visas which is a huge saving in time and stress..
Another good way to get your foot in the door is to apply to an accredited school while attending a university program in your home country. Armed with your student visa, you may legally work 20 hours per week. This may not be a lot but it is a start. You can make contacts and maybe one of those contacts will hire you and do all that is needed for a work visa. The Italian government has recently realized the ease of coming with a student visa and so has put up some obstacles. From what I have read on the various Embassy and consulate pages, you should have proof that you are currently attending a university program at home and that the course you will be taking will be something that you cannot find at your school.
If you are not an EU citizen, you need to have a visa to stay for longer than 90 days (total) out of any 180 day period. The old days of hoping over to another country for lunch are long gone. You now would need to leave the entire EU for 90 days before returning for another 90.
To get a work visa you will need to first find a job and then the company that hires you will have to supply many documents to help you get the visa.
If you are planning on getting an independent work visa there are many more problems entailed, most notably the quota on how many in each sector.
To apply for any visa you must do so at your Italian consulate in your home town (or the one that covers your home town).
If you are lucky enough to be retired than your road is much much easier. You will need to apply for an extended stay or long stay visa. You apply 90 days before you are planning on leaving. You will need to have proof of a place to stay, proof of an income to sustain you, medical insurance, a letter stating your reason for the move and a document from the police stating that you have never been convicted of a felony. For this contact your local consulate to find out where they recommend you get this document from.