The polite Hello in Liechtenstein is "Grüss Gott," pronounced: Grew Scott;  this is the formal, polite greeting used with strangers or older people. It's always a good idea to start whatever you're saying with hello.

In Liechtenstein, the familiar greeting is "Hoi" pronounced: Hoy;  this is the informal greeting to be used with friends.

Goodbye is "Wiedersehen" pronounced: Vee-Der-Zane.  You've heard it before I'm sure, but in Liechtenstein they leave off the "Auf."

The familiar goodbye used with friends is "Ciao," pronounced: chow just like in Italy.

Excuse me is "Entschuldigen Sie" pronounced: Ent-Shool-Diggen-Zee; that's a hard one, it takes some practice.

To ask "May I?" say "Darf Ich?" pronounced: Daawf-Ick. Motion with your hand and say "Darf Ich?" to ask permission for something.

Please is "Bitte," pronounced Bit-Teh.

Where's the rest room? is "Wo ist die Toilette, bitte?" pronounced: Vo ist dee toy-let-teh bit-teh? 

Could you please help me? is "Können Sie mir bitte helfen?" pronounced: Koo-nen Zee Meer Bit-teh Hell-fenn? 

Help! is simply "Hilfe!" pronounced: Hill-feh! 

Should you really need it, the word for Police is Polizei, pronounced: Poh-lee-tseye.

I'm Sorry is "Es tut mir Leid," pronounced Es-Toot-Mir-Lite, not too easy, either, but these politeness phases will go a long way in sending out good travel vibes. It's hard to go wrong with good manners, and the locals will appreciate the effort to use their language.