English is quite subtle in its formal and informal registers – you say “good morning” rather than “hi”, “how are you” as opposed to “what’s happening”.
But Italian has an entire grammar structure dedicated to formal language in the form of the third person “lei”.
So what does this mean when speaking everyday? If the person is older than you, or you don’t know them, you must always refer to them as if they were someone you were talking about, not to.
So, “come stai” becomes “come sta” (how is he or she?).
And “scusa” becomes “scusi” unless you’re speaking to annoying high school students and then you’re better equipped with an English expression like “get out of my way” or “you’re smoking in my face”.
And while we love “ciao”, it’s better not to use it.
“Ciao” is wonderful, it means “hello” and “goodbye” and “you’ve not a chance in the world”, and “as if”.
Such a small word, so many uses.
But when entering a shop, “buongiorno” is far more polite, “buonasera” is good for the restaurant when you’re out for dinner, and a firm “buona notte” is when you get rid of the guy who wanted to buy you a drink in the bar.