The percentage play for declarer to avoid losing two tricks in each suit is to finesse the 9 hoping that West holds the 10.
If the Q or K is played by East, declarer then finesses the Jack on the second round of the suit.
This will allow declarer to avoid losing two tricks whenever West holds either Q10x or K10x.
With this understanding in mind you as West must hope that declarer will go wrong and lose two tricks.
(a) When a spade is led, play low hoping that declarer plays the 9 to partner’s 10. You’ll then make one further trick with your KQ.
(b) When a club is led, try playing the King hoping that declarer will think you have both King and Queen. Hopefully declarer will win the Ace and then re-enter his hand and lead up to the Jack.
In both cases the defense makes 2 tricks.
OF COURSE, WHEN YOU PLAY THE KING FROM K10X OR SMALL FROM KQx DECLARER MAY PLAY YOU FOR THAT HOLDING IF THEY THINK YOU’VE READ THIS TIP!