A Let's Go Travel Guide, Austria and Switzerland (including Munich)
Austria section, p. 72 Culture, Customs and Etiquette
In general, following good manners from your own country will take you far in German-speaking ones. The rules aren't too different in Austria, although there are a few ways you can disguise your status as a tourist and impress the locals. For instance, most Germans and Austrians hold their fork in left hand and knife in the right, but don't switch them after cutting. While forking left-handed is hard, it can impress the locals (unless your schnitzel lands in your lap).
On the subject of cultural norms, Austrian residents or visitors, what is the sauna/spa (un)dress code?