Bishops of different colors favor the attacker. Make sure you attack first even if you have to sacrifice a pawn doing this.
If different colored Bishops are suddenly on the board after trading pieces you have to organize an attack running on the same square color as your bishop. At move 15 White brings his bishop to a strong position (15.Bd5) in the center, aiming at the black kingside. He intends to use all his remaining pieces to launch an attack against the black king.
This attack will be based upon the strong position of his white colored bishop at d5 that has no counterpart as Blacks bishop runs on black squares only.
The attack runs foremost on white colors because the bishop at d5 controls white squares! Black will not be able to stop a white-colored attack as he has no white-colored bishop!
So in chess watch all bishops and understand that if a situation of different-colored-bishops arises, you have to bring your own bishop to a stong center square where it will shoot at the opponents king. After that organize an attack with your remaining pieces (and use your king if necessary) on the same square-color as your bishop.
At move 23 Black gives a check with his bishop on f4 and brings this bishop in position. From now on his aim is to penetrate with his queen along the black squares into the white kingside.
The bishop from White is dead and inactive and plays no role as the attack is running on black squares which the white bishop cannot defend. So, in effect, Black is a piece up as the white bishop is useless. Replay this game below and study the procedure.