Assuming the pawn is on the 7th rank  These positions divide into two types.

      Type One = Kings in Opposition          Type two = Kings not in Opposition

 There are two  winning methods in these positions. If neither work the game is drawn.

                                           Zugzwang Method                                       
1 Kings in opposition with aggressor king toward the  rim of the board.                          

2 Drive defensive bishop to the short  diagonal  which must be three links or less.            

3 Challenge the defensive bishop.
4 Tempo to create Zugzwang.

                                              Shield Method

1 Kings are not in opposition.

2 Place aggressor bishop to to shield pawns stop square.

 
By examining the above methods it is clear that the choice of which method will be used is determined by the placement of the defensive king.

        IS  THIS POSITION A WIN  FOR WHITE  ?

         Click to play

Two questions to ask :

1 Are kings in OPPOSITION ? If yes can't use SHIELD METHOD

2 Is shortest diagonal 3 squares or less ? If yes ZUG METHOD