If you are staying near the Hauptbahnhof, most major tourist sites are within walking distance or can be visited via streetcar or subway.  Your hotel may sell transportation passes.  One of the best ways to orient yourself to the city is to take the Grey Line bus tour of the city.  It’s inexpensive and departs from in front of Herties Department Store, just across from the Hauptbahnhof.  Tours in summer run almost hourly during the day.  This will also give you an opportunity to judge whether you want to walk everywhere or take public transportation.  Much of the area within the Pedestrian Zone....about 6 blocks from Herties, is filled with interesting places to visit from churches to biergartens, as well as some small museums and lots of stores.  Renting a bicycle would be an excellent way to see Munich.  In Munich, bicyclists have the right of way, and the city has extensive bike trails.

MVV - Official Munich Transport System