There are four official languages in Switzerland, so you can say hello in German, French, Italian and Romansh (also called or Raetoromanisch). It is considered polite when you look into someone’s eyes and wish them with a smile.
In German: Say “Grüezi” to greet one person, or “Grüezi Mitenand” to greet two or more people.
In French: “Bonjour”
In Italian: “Buongiorno” during the day and “Buonasera” in the evening
In Romansh: “Bun di” for good morning. Pronounced as “boon dee”
“Buna saira” for good afternoon or good evening. Pronounced as “boon-a serra”.