On your first discard, you should be telling your partner, the suit that you would like them to come back to you if they are on lead again. An ODD [3-5-7] card in that suit says that you "Like" that suit. An EVEN [2-4-6] card will says that you "DisLike" that suit. Some advanced players will even show a High - Odd Card to tell partner to lead back the higher suit - i.e. a 10 of Diamonds will say Hearts if the trump suit is Spades. An Low - Even Card conversely would say, lead back the lower suit - i.e. 2 of Diamonds would ask partner to lead the Clubs if either the Hearts or Spades is the Trump suit.
If you see 2 Honours on the board [K,Q or J] and one is led, do not cover the first Honour, just the second if it is led again.
If the declarer leads a Jack from the Dummy and you are holding the King and the Queen in that suit, always split your honours by playing either the King or Queen even if their Ace takes this trick.