The long taught Simandl method uses only the first, second and fourth fingers to 'fret', with the third finger acting as a support for the fourth finger. Like any other instrument, as the years have gone on new styles have developed and many more contemporary players finger a DB similarly to an electric bass. It is important to have your left wrist and forearm angle correct (your elbow should be elevated, not dangling loosely, in a sort of arrow shape) to maintain positioning and stamina.