This position is from a recent club skittles game. Black has just blundered with 18... Qd7 thinking that he is offering a trade to reduce the pressure. In the actual game White quickly played 19. Qxc7. Can you spot a better move for White? See the solution after the fold:
Better would be 19. Rxf6 with a removal of the guard. Suddenly Black's protecting knight is gone and replaced by White's new protector, the rook. Black is left with nothing better than 19... Qxc6, admitting the mistake and giving up a whole minor piece.
How can you spot opportunities like this one? Always look for checks, captures, and threats. And for both players, check for loose pieces.
What should Black have done to avoid the situation? Always make a last check for safety before making a move. This check should include considering what your opponent's best reply will be, and what plan you have against that reply.