Signals are used only on defense. Do not Signal Dummy. And Dummy does not Signal Declarer. (This would be a major impropriety.) And Signals are done only with the cards. Gestures, grimaces, moss code, winks, kicking, and cell phones are not to be used. Let the cards do the talking.
There are 3 basic Signals in Bridge.
can be the cause 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
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.
| t used
primarily against a suit contract. t usually only two suits are Preferenced. t the suits are not trump and not the suit being led. t 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 Low Card |
HIGH
RANKING SUIT play or lead High Card |
If you want your Partner to return
the Lower
ranking of the two Preferenced suits, then play a low card. If you want
your partner to return the Higher ranking of the two 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.
In EXAMPLE
1. below you are sitting West and lead the A 
against a 4 Spade contract. Your Partner sitting East plays the 8 .
This can not be an Attitude Signal since the Q
is sitting in Dummy. So the 8
is the start of a high/low signal showing an even number. In this case
hopefully a Doubleton. (A Singleton is also good.) You continue with
the
K and your
Partner
completes the signal by playing 2 .
Declarer follows suit. If Declarer started with 4 Clubs you want your
Partner
to trump Clubs two times. But if your Partner trumps the Club at trick
three, how does he know how to get back to your hand? Is it with a
Diamond
or a Heart. Here is where the Suit Preference Signal comes in.
| 1. | DUMMY
 A Q J  10 9  K J 8 7 6 Q 9 7 |
|
| WEST
9 6 6 5 4 3 A 4 3 A K10 3 |
EAST
5 4 2
J 8 7 2 9 5 2 8 2 |
Consider that the two Preferenced
suits:
not the suit being led (Clubs) and not Trump (Spades). That leaves
Diamonds
and Hearts. You obviously want your Partner to return a Diamond after
he
trumps the first Club. So lead the 3 .
This signal says: the 3
is low, so return a Diamond. (The lowest of the two preferenced suits.)
If as in EXAMPLE 2. you had the A ,
then play the 10
at
the third trick. This signal says: 10
is high, so return a Heart.
| WEST
2. 9 6 A 5 4 3 10 4 3 A K 10 3 |
In EXAMPLE 3. below your
Partner
leads the A
against
a 4 Heart contract. Your Partner will not continue Spades and will make
a switch to one of the two Preferenced suits: Clubs or Diamonds. (Not
trump
and not the suit being led.) But which one will your Partner choose?
You
can help him out with a Suit Preference Signal.
| 3. | DUMMY 3 A 9 8 7 6 Q 10 9 Q 8 5 4 |
|
| WEST A |
EAST 10 8 2 9 6 A K J 3 7 6 3 |
Play the 10
on your Partner's lead of the A .
The high 10 says: "Partner lead the higher ranking of the two
Preferenced
suits which is Diamonds." If Partner sees and reads the signal the
hand will most likely be set.
If your
Clubs
and Diamonds were reversed; you had the
A K J 3 of Clubs and the 7 6 3 if
Diamonds
you would signal with the 2 .
This says "Partner lead the lower ranking of the two Preferenced
suits
which is Clubs."