The most convenient way is to train! The journey takes approximately 3 hours The train departs from the western railway station (Wien Westbahnhof), the station can be reached by metro - the U3 / U6 branch. The ticket price is from 19 to 50 EUR (2 class) - depends on the how much time you will get a ticket, that is, for a month or the day you leave for Salzburg

Schedule can be viewed here

From Vienna's Western Railway Station regularly (about once an hour) go to Salzburg train West-Bahn and ÖBB. On West-Bahn train tickets can be bought directly on the train