ArohemQ: I agree with
hamburger: learn "standard" German first, then work on any kind of dialect.
Despite appearances to the contrary, Austrians can actually understand and speak standard German -- even if they don't use it on a day-to-day basis. You should be aware of certain terminological differences between Austrian German and German German, just as you should be aware of terminological differences between American English and British English. Many German grammar guides will have a section on these differences (I can personally recommend
Martin Durrell's "Using German"). For instance, North Germans will use the -chen ending for diminutives, while Austrians and South Germans prefer -erl or just -el (thus it's Haensel und Gretel, not Haenschen und Gretchen).
As for more obscure points of dialect,
Walter has provided some good links -- although I'm surprised that "gemma" is not listed anywhere. In general, a couple of days in Austria will have you understanding what a "Fiaker" or a "Krapfen" is. In any event, I found that the accents are tougher than the vocabulary, and the only way you can learn those is by listening to native speakers (and for helpful operettas,
hamburger, I'd recommend listening to "Im Weissen Roess'l").
