If you plan to travel Faroe by public transportation, looking at below maps is a good starting point. Once you pick a line, You can find the timetable at
http://ssl.fo/
Some travelers suggested that you may need to make a phone call in advance to let the bus driver know you wanna take the bus, but the information center told that buses and ferries are quite punctual so you don't need any prearrangement.
Bus 300 is the most important one, assuming you are staying at Torshavn. 300 will bring you to Torshavn from the Vagar airport. It costs 90dkk one way (as of 2012) The route is very beautiful.
Here is how to read the time table.
* Dag = days of operation
* Flogv. = Airport
1, 2, 3, 4, 5, 6, 7 are Monday, Tuesday, ..., Sunday, respectively.
x means Monday to Friday (weekdays)
So, for example, on Saturday, there is no bus to the airport from Torshavn departing at 6:50AM