Mistakes for first timer in Switzerland staying in Dietikon/Zürich

Will be staying in Dietikon late Sept via a HomeExchange. What are some mistakes you see non-locals (ok tourists 😁) make? Ex: Chewing gum on the train, being a super loud American, drinking in public? I want to be respectful of the area since it's more residential and enjoy my time while soaking up some history and culture. Is there a food item I just can't skip out on?