Saying hello in Switzerland
I'm sure you're familiar with using Du (informal) and Sie (formal). To say hello in Germany informally, you can just say 'Hallo!', while formally it's of course 'Guten Tag'. You can use 'Tschüß' to say goodbye to everyone, though I've heard it wasn't always the case, but rather a recent trend.
However, this isn't the case in Switzerland - 'Tschüß' should be used only informally, and is considered rude otherwise. Better to say 'Ade' instead (for example when leaving a shop). The informal greeting is 'Hoi!', and if there's more than one person, say 'Hoi, mitenand!' or 'Hoi, zäema!' The formal greeting is 'Grüetzi', and again you'd use this when entering a shop, but not to say hi to your buddies.
Hopefully that isn't too confusing - here it is again in a table:
English/High German/Swiss German
Informal Hello / Hallo / Hoi
Formal Hello / Guten Tag / Grüetzi
Informal Good bye / Tschüß / Tschüß
Formal Good bye / Tschüß / Ade
I hear Bavaria is another story altogether...