Source: Richmond Bridge Association


1- When a trump is led on the get go, assume the opening leader does NOT have the queen and play accordingly.
  North (Dummy)  
  K 10  
9 7 6 3   Q
  A J 8 5 4 2  
If a spade is led against your spade contract, play the king from dummy. East is marked with the queen and it may be singleton. If it is, you save a trick. 2- When the opening leader makes a potentially ambiguous honor card lead such as the jack at notrump which could be top of a sequence or from the KJ10 or AJ10, and as declarer you have the AKQ, take the trick with the queen, the honor card third hand knows you hold regardless what the lead shows. 3- Conceal your strength by playing the highest immaterial card you can when an opponent shows out.
  North (Dummy)
  7 5 4
K J 9 3  
  A Q 10 8 6 2
Hearts are trump and you lead a low heart from dummy, East showing out! As long as you don’t intend to play the ace, play the queen, the highest immaterial card you can to conceal the position from East. If you play a lower card, East will have a better feel for West’s strength in the suit. Also, do not ponder over your play which gives East gratutitous information. 4- Do not squander honor cards haphazardly.
  North (Dummy)  
  A J 2  
K 9      10 8 7 6 3
  Q 5 4  
For three tricks lead low to the jack. If West has Kx, the ace will snatch the king and your queen is high. If you start with the queen, West covers and you only have two.
In a similar vein:
  North (Dummy)  
  K 10 9 2  
Q     A 8 7 6
  J 5 4 3  
For three tricks start with a low spade intending to insert the 10 if West plays low. Your play gains a trick when West has a singleton queen.
5- When you have a plethora of honors and spot cards, it still may be right to lead a spotcard rather than an honor as an entry conserving play. 
  North (Dummy)  
  A J 10 2  
K 8 7 6    5 4
  Q 9 3  
 Say you need 4 diamond tricks and have no reentry to your hand. If you start with the queen and West plays low, you can only take three. After you repeat the finesse by leading low to the ten, you cannot get back to your hand to repeat the finesse. However, if you start with the 9 and West plays low, you can underplay with thedeuce and then then lead the queen. Now you have four tricks regardless. Similarly: 
  North (Dummy)  
  K 10 9 2  
Q 7 6 5    A 4
  J 8 3  
Say the lead is in your hand and you need three diamond tricks and have only one hand reentry. If you start with the jack and West plays low, East wins the ace and now you cannot pick up West’s queen with only one hand reentry. However, if you start with the 8 and West plays low, you can underplay the deuce. Assuming East wins the ace (it doesn’t matter), you can return to your hand and lead the jack losing but one trick in the suit.
6- Notrump; with a choice of two finesses and only stopper remaining in your weakest suit, ask yourself which finesse, if it loses, leaves you with the most REMAINING tricks.
North (Dummy)
A Q 9 4 3 A 9 6   A 9           K J 5
J 10 J 8 4 3   K 2         A 10 9 8 7
West North East South
  1 Pass 1NT
Pass 2NT Pass 3NT
The End      
Opening lead: Q
Should you attack spades or clubs? If you attack clubs and the finesse loses, you remain with 8 tricks: 4 clubs, 2 diamonds 1 heart and 1 spade. If you attack spades and the finesse loses you remain with 9 tricks: 4 spades, two clubs, 2 diamonds and 1 heart. Attack spades. 7- When no line of play looks clear, consider “scrambling” (ruffing in the long hand).
North (Dummy)
10 8 Q 3  A J 3 2           9 8 7 6 5
Q J 5 3 2 A K 7 6   7      J 3 2
West North East South
Pass 1NT Pass 2
Pass 2 The End  
Opening lead: K Your best bet for 8 tricks is to embark on a mini-crossruff. Win the A; ruff a diamond; cash the AQ of hearts ending in dummy and ruff another diamond; ruff a heart with the 8 and ruff your last diamond (if you can) reducing to the blank QJ of spades. You have scrambled for seven tricks and now all you need do is ruff the K with the 10 to ensure an eighth. 8- When you have a CONCEALED running suit, try to steal your contract making trick early-before the opponents can count your tricks.
North (Dummy)
A 4 8 5 4 J 5 4 3           Q 5 4 3
K 2 J 10 6   A K Q 10 7 6      K J
West North East South
    3 3NT
The End
Opening lead: 9 Win the A and casually lead a low club to the king. Assuming West takes the trick, West is going to have to shift to a heart to defeat this contract. Not easy since West doesn’t know about all of those diamond tricks you have lurking. However, if in a panic you run your diamonds first, it will be much easier for West to shift to a heart upon winning the A. 9- When the dummy has more trump than you do (usually after a transfer sequence) treat your hand as the dummy and try to trump partner’s losers in your hand, the shorter trump hand. Some players have to stand on their head to see this.
North (Dummy)
K Q 10 6 5 4 7 3 2 2          K 5 4
A J 3 Q J    A 8 7 6      A 8 6 3
West North East South
Pass 4 Pass 4
The End
Opening lead: Q You have six spade tricks, two clubs and one diamond for nine. The easiest road to 10 is to ruff a heart in your hand, the short trump hand. Win the A and lead a heart. When you regain the lead, lead a second heart eventually trumping a heart in your hand for your 10th trick. If you draw trump first and trumps are 3-1, you will find up losing three hearts and a club. 10- When partner leads a suit at notrump and then discards several cards from that suit, he does not want that suit returned; look elsewhere. Dlr: North Vul: Both.
  North (Dummy)  
  A K 10 3 2 A 7 6 2 3          J 5 4  
Q 7 6 K J 9 3    5      A 10 7 6 2   J 9 8 4 10 8 4 Q 10 8 7       8 3 
  5 Q 5    A K J 9 6 4 2    K Q 9  
West North East South
  1 Pass 2
Pass 2 Pass 3NT
The End      
Opening lead: 6 Dummy wins with dummy’s jack South takes a winning diamond finesse. When he cashes the AK of diamonds West discards clubs. When East wins the 4th diamond he should shift to a heart and not continue a club. Had West wanted a club continuation he would not have discarded clubs. 11- In this common position it is almost always right for East to duck the first round of the suit when declarer leads the queen and is known to have a doubleton from partner’s count signal.
  North (Dummy)  
  K 10 6 4 3  
9 8 2    A J 7
  Q 5  
12- When discarding at notrump or even at a trump contract where getting a ruff is not an issue, avoid discarding from short suits, particularly short suits where you cannot see the queen in dummy. You may be exposing partner’s queen to a finesse in a two way finesse position. It is usually right to discard from unimportant length.