Discard only once from your strength, and then as the situation and the hand warrant.
THE REVERSE DISCARD
In discarding, the play of a high and then a lower card reverses the original meaning of the discard. If you adopt the strength discard, and wish to throw away your weak suit at "no-trump," do so by discarding first a high and then a lower card. If you use the weak discard and wish to throw away your strong suit, discard first a high and then a lower card.
The reverse discard should be used only when it is clearly shown that two discards can be made.
HINTS ON DISCARDING
Watch the dealer's discards and protect the suit that he is saving.
After you have led or shown your suit, the discard of a high and then a lower card in another suit shows command of the second suit.
The discard of an Ace shows great strength in the suit.
If a spade declaration has been doubled by you or your partner—and especially when either of you has indicated strength by leading trumps—the first discard should be from weakness.
In discarding at "no-trump," don't throw away all the cards of one suit: it exposes your partner's hand, and makes it easy for the dealer to tell how that suit is placed. Besides, you may need one card of that suit to put your partner in the lead.