HERE ARE MY TIPS:

You pronounce written words differently in both casual and formal situations:

- "ham" ("haben")

--- "Wir ham nichts zum Trinken" ("Wir haben nichts zum Trinken")

--- "Ham Sie unsere Email bekommen?" ("Haben Sie unsere Email bekommen?")

- "nich" ("nicht")

--- "Findest du nich, dass ist dumme Idee is?"

- "is" ("ist")

--- "Das is ein toller Vorschlag!" ("Das ist ein toller Vorschlag"!

- Alle Endung mit -er: are pronounced -a

--- schöner = schöna

--- hübscher = hübscha

--- aber = aba

--- Bruder = Bruda

--- Schwester = Schwesta

- some words with the ending "ig" are pronounced "ich"

--- richtig = richtich (I can't think of more now

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Vokabular:

"Sackerl" (mostly a plastic bag that you buy in the supermarket but it could also be a normal bag)

"Heferl" (cup where you drink your coffee/hot chocolate in, it's not a glass)

"Zuckerl" (A bonbon)

"Servus" is very strange. I simply say "Hi" or "Hey" when I greet my friends

"Grüß Gott/Hallo" is used to greet formally

Again, don't talk in dialect, only people who live in that are will like you/you will come across strange to other german native speakers. If you wanna live only in Bavaria, fine, do it, but it'll destroy your german language.

- My opinion though

I'd admonish you to speak in dialect @Jott Be's examples are used to imitate drunk people. Nobody with there senses intact would talk like that. And I am from Austria!

- "do san mer dahoam" --> hier sind wir Zuhause ... would someone use after he opened a bottle of beer (for illustration purposes)

- "wo kimst denn du her?" --> wo kommst Du her? ... If you are suprised that someone accidentally appeared in the room, you would use that one, like "Oh, well, look who's here". It DOES NOT MEAN "Where are you from?". "Where are you from?" would mean "Woher kommst du?/Von wo bist du?

I don't know Austrian and Bavarian dialects, but I know that there are in standard German some words which are different, from Germany to Austria (and Bavaria too), due to cultural and historical reasons (in Austro-Hungarian Empire, 11 official languages were spoken (German, Hungarian, Italian, Slovenian, Croatian, Serbian, Czech, Slovak, Polish, Ukrainian and Romanian) and each of them gave and soaked up something with the others.
You can see a few of this words here: Was esst ihr? (http://www.italki.com/discussion/77998)
and a lot of them here: http://de.wikipedia.org/wiki/Liste_von_Austriazismen
this one can also help: http://en.wikipedia.org/wiki/Austrian_German ;

Woas is denn dess füa frag?

I am not Bavarian, I better leave it to other. But I remember some AT movies (Die Aufschneider, Kottan Ermittelt) and some of the dialoges (vianna slang?) had subtitles. 

Thanks! I think I will follow everyone's advice and not worry about learning any dialects.  :) 

Thanks again everyone!