Important advice for tourists
Venice is a city utterly over-run by tourists. But Venice is also home to thousands of people going about their everyday business (and they're not all dependent on tourists for their livelihoods). So visitors should bear in mind that that is what they are - visitors - and make an effort to behave appropriately.
Plaintive little pleas from the council are plastered around the tourist sights urging tourists to behave with decorum. There is even a new awareness-raising 'decorum week' with a parade of boats down the Grand Canal. And the threat of fines for picnickers and bare-chested men. I won't advise you not to drop litter; that goes without saying. But some local 'rules' of behaviour are less obvious so I've done my best to come up with some advice that will help you to give tourists a good name.
Walk on the right
This is the norm in Italy, and in several other countries too. Visitors from the UK, where we favour freestyle walking, can take a long time to tumble to this. In Venice, where the narrow lanes are thoroughfares used by all, tourists and busy locals, this is absolutely vital. You should keep to the right, always allowing room for others to pass (stick to single file when necessary). Keep to a brisk pace on busy paths. If you want to stop to look in a shop window or consult your map, pull in, removing yourself from the stream of traffic just as you would if you were driving. Spare a few moments to imagine what it must be like for those who have to take these tourist routes every day to get to their office or run urgent errands.
Don't block bridges and don't picnic
On a similar note, don't obstruct bridges. If you must stop on a narrow bridge to admire the view (and in picturesque areas, it's hard not to), keep out of the way and don't cause a traffic jam. Do not sit on bridges to eat your lunch unless you want to infuriate hundreds of passers-by. Public picnicking, incidentally, is frowned on in general and in some areas it's banned. From time to time the police threaten to fine people attempting to eat in public places around St. Mark's Square; I've seen picnickers being moved on. Try to find an out-of-the-way spot where you can sit decorously on a bench.
And next, be considerate on boats. Venice's ferries get very crowded. Boatmen will often urge passengers to move forwards ('avanti!') and to find space inside the boat. Tourists who hang around near the gangplanks will prevent other passengers from getting on and off, and will win themselves no friends. Don't be too worried about getting through the crowds when you reach your stop. Once your ferry has moved off from the preceding stop, head for the exit, uttering a firm 'permesso' when you need to pass someone. Take off your rucksack when you're on a boat.
This is necessary if you want to enter churches or monuments. Women and men should basically be covered from the collar-bone to the knee, or as near as possible. Shorts and bare shoulders will give offence and may result in you being barred from religious sites, though a scarf or sarong can save the day. I've seen tourists with sleeveless tops turned away after queuing at St. Mark's.
Don't dress for the seaside. If you're visiting the beaches at the Lido, by all means (un)dress appropriately. But away from the sea, Italian men do not go bare-chested, and both men and women tend to cover themselves up more than the British or Americans. (Women often dress provocatively but not in a whole-expanse-of-skin way like Anglo-Saxons). Some Italian towns are so offended by scantily-clad tourists that they have introduced by-laws banning bikinis and bare chests on the streets. Venice joined them in 2007: men - if you go bare-chested you will offend other people and you could get hit by a big fine.
It’s only good manners to learn a few phrases in Italian - at the very least, you should master 'please', 'thank you' and 'do you speak English?'.
Thank you : Italy Heaven