Swap Pawns not Pieces
Swapping pawns rather than pieces is an endgame strategy used when a player is losing. The aim is to achieve a draw by removing all the pawns, in which case no-one can create a new Queen. If all the pawns are gone, pawnless endings tend to be drawn.
Although pawnless endings is the ideal draw, another type of position is very drawish: when all the pawns are on one side of the board. So the player seeking a draw should try to at least swap off all the pawns on one side of the board, whereas the winning player should try to keep pawns on both sides of the board for greatest winning chances in the endgame.
The other part of the strategy is keeping the pieces (avoiding piece swaps). There is more possibility of active resistance with more defensive pieces. Winning a King-and-Pawn endgame is easy when up a pawn or two. There is the greater chance of counter-attack and active defence with pieces on the board. Also it is more likely that they may be mistakes and traps. And the final point is that if you keep pieces, sometimes you can sacrifice a Bishop or Knight for the last pawn or two, to reach a drawn pawnless ending.
Related Chess Tactics
Read more about these related chess strategies: