How to behave in Rome...

Italy has a reputation for being warm and welcoming. Here are some general comments on Italian culture, and some tips for adjusting to Italian manners and standards. Obviously this is mostly based on personal experiences; generalisations of course do not always hold true.
When in Rome...

Greetings
Italians greet friends with two light kisses on the cheek, first the right and then the left. Even if you're merely acquaintances, this form of greeting is usual, both on arrival and departure. When groups are splitting up, expect big delays as everyone kisses everyone else. On first introduction a handshake is usual, although not necessarily the firm businesslike shake other nationalities may be used to.

Foreign reserve
If your inbred cultural reserve makes you feel uncomfortable with this, don't worry too much. The British in particular have a reputation for being reserved, so you can always play up to this expectation, and Italians will understand you don't mean to be rude. Handshakes are also accepted greetings, and some Italians will kiss compatriots and offer their hand to the awkward Brit.

Shops
In a small-medium sized shop, it's standard to greet the staff as you enter, not when you approach the counter to pay. A friendly 'Buongiorno' or 'Buonasera' warms the atmosphere. When paying, we've found that staff usually expect you to put coins down on the surface or dish provided, rather than placing money directly into their hands (fear of germs? money-handling etiquette?), and they will do the same when giving you your change (il resto). The advent of the euro has caused problems for the Italians. Most lira transactions were in banknotes, and people are still adjusting to the fact that coins are now of significant denominations and in general use. Don't be surprised to find the whole issue of change rather perplexing for cashiers, who may try to insist you give them complex combinations of coins and notes rather than simply changing your notes.

Making friends
To make friends, it's a good idea to pay some compliments. Most Italians still live in their town of origin and feel far more strongly about their local area than they do about Italy in general. Tell them how beautiful their town/lake/village/church is - and possibly add how much you prefer it to Rome/Milan/other Italian towns. Residents can be founts of knowledge regarding their local monuments and history, and a few questions will often produce interesting stories.


Clothing
Whole essays can be written about the Italians' relationships with clothes (maybe a future addition to this site...). Three of the most important observations:
1. Italians are very conformist about clothing; everyone wears the same fashions, from teenagers to grans (this can take some getting used to... see comment 2 below). Don't be surprised or insulted if you are looked at askance for your 'eccentricity' in not wearing the latest customised jeans or fiendishly-pointed boots.
2. It's important not to judge people in return by their choice of clothing. Styles do not necessarily carry the same connotations in Italy that they would in Britain or some other countries. A women in fishnets, stilettos, miniskirt and caked makeup at eight in the morning is probably just going to work in a bank. Almost all youths lounge about in skin-tight t-shirts and casually-knotted knitwear (and are very perplexed by the response they get when they take their sense of style and grooming to a less 'sophisticated' climate).
3. Sometimes clothing rules are written. To visit a church or religious site you will need to cover yourself up; no bare backs, chests, shoulders and sometimes no knees. Sometimes museums and other attractions can also be strict; no bathing costumes, for example. If you want to visit a church or religious site it's a good idea to take something to cover yourself up with; for example a jumper or large scarf. Some churches supply cover-ups, e.g. sarongs are loaned to men with shorts so that they can modestly conceal their legs. Even where there are no written rules, it's worth noting that bare chests and large expanses of sunburnt skin aren't really acceptable away from beaches or sunbathing areas, whatever the temperature.

Advice for women
Sexual harassment is not regarded in the same way in Italy as in English-speaking countries. The general atmosphere is pretty unreconstructed, and women should be prepared for attention. However, the tone of this 'attention' is generally less aggressive than you may be used to. Men will call out compliments such as 'bella' (beautiful) instead of muttering crude suggestions. And culturally, these comments are not seen as insults; if you respond angrily or insultingly everyone will be very surprised. Whereas women of other nationalities may be used to telling strangers (in no uncertain terms) to shut up and go away, in Italy the norm is to ignore the attention. In any case, responding in English or in imperfect Italian will only encourage more attention. It's best to do as the Italian women do, and sail past with your head held high. If you avoid eye contact and don't respond, you are extremely unlikely to be pursued or hassled further.
(source)