Trade pawns in the center to open up diagonals. The fewer pawns there are in the center, the more scope your bishops will have. Aiming both of your bishops at the opponent's king also increases the chance for tactical and mating combinations. Remember, without pawns in the center, enemy knights won't be able to use a centralized outpost.
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[Event "rated untimed match"]
[Site "?"]
[Date "1787.??.??"]
[Round "?"]
[White "Legal"]
[Black "Saint-Bris"]
[Result "1-0"]
[Annotator "David Hayes"]
[BlackElo "0"]
[ECO "C23"]
[TimeControl "0"]
[WhiteElo "0"]
{ Legal's Mate:|This game was played in 1787. It is one of the shortest and
prettiest games ever played. The final position was named after the winning
player, Legal's Mate. } 1. e4 e5 2. Bc4 d6 3. Nf3 Nc6 4. Nc3 Bg4 { We reach the
critical position where the knight on f3 is pinned against white's queen.
However, the pin is not absolute. } 5. Nxe5 { What is this? The knight moves
exposing its queen. } ( { Later in 1929, The French master Cheron was aware of
the incorrectness of the immediate Nxe5 and played this line against an
amateur. } 5. h3 Bh5 6. Nxe5 Bxd1 ( { Black can try: } 6... Nxe5 7. Qxh5 Nf6 8. Qe2 { Leaving white a whole center pawn up. } ) 7. Bxf7+ Ke7 8. Nd5# ) 5... Bxd1 { Black's greed is quickly punished. } ( { You don't need to be a grandmaster to
see that this line goes a solid knight up for a pawn. } 5... Nxe5 6. Be2 Bxe2 7. Qxe2 { Black wins with a large material advantage. } ) 6. Bxf7+ Ke7 7. Nd5# 1-0