Suit Preference Signal
          Counting Partner's Hand          ` 
Playing Bridge is not only bidding and playing the hand; it is also Defense: preventing the Declarer from making the contract. And part of defense is Signaling.
         Signals are used only on defense. Do not Signal Dummy. And Dummy does not Signal Declarer. (This would be a major impropriety.) Signals are done only with the cards. Gestures, grimaces, morse code, winks, kicking, and cell phones are not to be used. Let the cards do the talking. 
      There are 3 basic Signals in Bridge.
                      Suit Preference
In order to avoid confusion, and there might be some when you first use signals, (and maybe even later), let the Attitude and Count be a preference over Suit 
Preference. Actually Attitude should count more than the Count. Misuse of Signals
can be the cause of disastrous defensive errors and can lead to partnership break- up, divorce, bodily injury and possibly even death. But do not be discouraged; the rewards are great. Still, make sure partner is not armed.

Suit Preference Signal
This is probably the most complex and abused of the 3 Signals. Does this mean 
we should not use the Suit Preference Signal.? NO! After all, cars are complex; does that mean we should ride a horse. (Which is also complex in its own way.) Some people say that complexity and abuse are what make Bridge a great game. 
      But enough of this. Let's see how Suit Preference works. 
  w   used primarily against a suit contract.
  w   usually only two suits are Preferenced.
  w   the Preferenced suits are not trump 
       and not the suit being led.
  w   that leaves 2 suits. The higher 
       ranking suit is Preferenced by 
       playing or leading a high card; and 
       the lower ranking suit is Preferenced 
       by playing or leading a low card. 

                LOW RANKING SUIT
             play or lead a Low Card

               HIGH RANKING SUIT
            play or lead High Card

If you want your Partner to return the Lower ranking of the 2 Preferenced suits, 
then play a low card. If you want your partner to return the Higher ranking of the
2 Preferenced suits, then play a high card. Do not worry if Declarer knows this 
information. Your partner will make better use of this information than the Declarer. 
      More important is to have a Partner who can see and read the Signals. This is
what makes for an efficient and effective defensive team.. 

Over North's opening bid of 1 C, East overcalls 1 H. This shows a 5+ card Heart suit headed by 2 honors and 10 or more points. 
       South competes by bidding 1 S. This bid shows a 5+ card Spade suit with at least 6 points. North shows Spade support and a Minimum opener (13 - 15 points) by rebidding 2 S
      South, with 15 High Card Points (HCP),  knows that they are in the game zone of 26 points (15 + 13 = 28). But, if South considers distribution points, with a doubleton in each of the Minors, then they are near the slam zone of 33 points. Near, but not in; South bids game at 4 S. All pass. 

The Opening Lead can make or break a contract. So, it is important to get off to a good start. Even though Opening Leads might seem like a shot in the dark, there should be a message for partner behind every lead. And hopefully, partner will get the message.
        There are two reasons why East should lead the 2 H. The first reason is that the suit bid by his partner was Hearts. Thus, it is likely that partner has some goodies (Bridge tech term) in Hearts. The second reason is that the 2 H is a singleton. West could potentially win  the second or even third round of Hearts by ruffing. 

Dummy comes down. Declarer is thinking and counting. East should be doing the same. Should East play the A H or the J H ? Does West have the Q H ? Is the 2 H the bottom of fourth best in Hearts? If East examines the clues, the answers are there. Bidding Clue: partner did not support the 1 H overcall and probably has less than three Hearts. Spot Clue: if partner started with a doubleton in Hearts, he would play high then low. Since the 2 H is the lowest Heart, partner did not have a doubleton Heart. Conclusion: the 2 H must be a singleton. 
      After reaching this conclusion, the play is sort of obvious: win with the A H and give partner a ruff. But that is only 2 tricks. And with the A C, this makes 3. Not enough to set the hand. Maybe partner has another trick. 
      Again, examine the clues. Declarer has at least 12 points because she went directly to game over her partner's minimum support. Now count: Dummy has 14 points and you, East have 11. Add them up: 12 + 14 + 11 = 37. West cannot even have an Ace. Possibly, but not likely, the K S
       The best shot at setting the contract is to have West ruff Hearts two times. These two tricks, plus the A H and the A C will defeat 4 S. In order to do this, West must return a Club after he ruffs the first Heart.  The A C is the only entry back to East's hand. But how to tell West to lead a Club after ruffing the first Heart? Answer: use the Suit Preference Signal.
PLAY: East wins the opening lead with the A H. East is pretty sure the 2 H is a singlton and that his partner will ruff the next Heart. But what Heart should East play? Here is the chance to use the Suit Preference Signal. First, find out what suits are Preferenced. Simple; eliminate trump (Spades) and the suit being led (Hearts). That leaves the Minors; Clubs and Diamonds are the Preferenced suits. East has the A C, the lower of the two Preferenced suits. Thus, he leads the low Heart (3 H), signaling his partner that he wants the lower Preferenced suit (Clubs) returned. 
        West ruffs and reads his partner's message and returns a Club. West wins with the A C and plays another Heart. West ruffs for the second time which is the setting trick. The Defense took the A H,  A C, and two Heart ruffs for down 1.
       There is no such thing as a bad hand, only bad players. Note that West, with a Yarborough (no honors), took 2 tricks.

1. If East had the A D, what Heart would he play at trick 2?
2. If West does not return a Club at trick 3, could Declarer make the hand?

After the Defense takes the first 4 tricks, setting the contract, the play of the hand is quite straightforward. Pull trump and take the rest of the tricks.
       However, there are some deceptive plays that South could make on the opening lead.
       Play the K H from Dummy at trick 1. The only reason for a Declarer to do this, is that she does not have the Q H. This might induce East to think that his partner has the Q H. East starts to think: " Since partner has the Q H, we can get that later. I'll try another suit." 
       Another deceptive play at trick 1 is for South to play a small Heart from Dummy and then bang down the Q H from her hand. This deceptive play can also cause the wheels to go round in the wrong direction in East's head: "South has a singleton Heart and my partner started with 4 Hearts and the 2 H is from the fourth best. Therefore no sense returning a Heart"
      It is important for Defender to think things through. But, with deceptive play on the part of Declarer, the thinking may go awry.