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, the staff usually expect you to put coins down on the surface or dish provided, rather than placing money directly into their hands (old money-handling etiquette to avoid messy coin droppings), 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.