When to trade pieces
It's usually helpful to trade if you can get ahead but what should you do if a potential trade doesn't gain or lose material? It's usually a mistake to initiate a trade unless you can tell how your position benefits. Good reasons to trade could be to simplify when you're ahead, to remove a well placed opponent's piece or to gain control of an open file.
Black is attacking White's knight on d5. Can you find a trade that will lead to winning material for White?
White trades minor pieces, forcing Black's queen on a dangerous diagonal. Can you find a skewer that wins material?
White's bishop skewers the queen to the rook, when White will win an entire rook!