Here are 12 useful guide lines (6 for the Declarer and 6 for the Defence) to consider and remember.

DECLARER PLAY
1. In NT contracts DEVELOP the additional tricks required for your contract BEFORE cashing in your sure winners. This means losing the lead early while you still have your stoppers in hand.
   
   In TRUMP contracts usually DRAW TRUMPS FIRST, unless you need to ruff in Dummy or to get rid of some losers first.
   
   
2. When running a suite : play the HIGH CARDS from the SHORT side FIRST, for example :
              with   ♥ - A Q x   opposite Dummy's   x x x x K - ♥
   First play the A and Q, only then lead the small Heart to Dummy's K.
   This way you can play all 5 tricks in the suit without the need for another side entry to Dummy.
   
   
3. In most cases ONLY draw opponents' LOSING TRUMPS :
   ♠ - A K x x   opposite   x x x x - ♠   >   Draw trumps only twice   >     >  ♠ - x x     x x - ♠
   Then force the opponent to ruff a trick from one of your side suits.
   This leaves you then with 4 trumps instead of only 2.
   
   
4. Indirect finesse = leading a LOW card to a HIGH one   (you try to avoid Opponent's high card)
   Direct finesse   = leading a HIGH card to HIGHER one   (you try to catch Opponent's high card)
   Only play a Direct finesse when you hold 4 of the 5 Honour cards.
   
   A Double finesse towards A Q 10 or A J 10 has a 75% chance of gaining 2 tricks.
   A Double finesse towards K J x has a 75% chance of making at least 1 trick.
   For any Single finesse (towards A Q (x) or K x (x)) the success rate is 50%
   With 8 cards or less, double finesse!   (Double finesse = leading up to the lowest Hounour card first.)
   
   
5. When the four HIGH cards in a suit are divided amongst all 4 players DO NOT LEAD that suit (unless you hold also the 10), but let your opponents do that for you. (This applies equally to the Defence.)
   
   
6. When opponents hold an ODD number of cards in a suit they will 65% of the time break EVENLY :
   5 cards   >   >   3 + 2
   When opponents hold an EVEN* number of cards in a suit they will 65% of the time break UNEVENLY : 6 cards   >   >   4 + 2 or worse     Therefore avoid 4+3 trump suits, a 5+2 holding is not too bad.
   
   * Exception: When the Opponents hold only 2 cards in a suite they are divided 1-1 almost 50% of the time.

DEFENCE
1. About Leads
   1. Top of a solid sequence (or top of 2 touching Honours in a trump contract) is always a good ATTACKING lead. It will force out an Ace, or set up a direct finesse against an Honour in Dummy.
   2. Lead K from A K x (x) to "have a look at Dummy".
   3. AVOID leading AWAY from a KING

   4. NEVER lead AWAY from an ACE in a Trump contract
      (In NT leading 4th from A x x x is OK)
   5. AVOID leading an ACE in a Slam Contract (you make it just too easy for the Declarer!)
   6. AVOID leading away from a Tenace (A Q or K J)

   7. In NT with no other indications lead 4th from your longest suit.
      In Trump Contracts a trump lead (from xx or xxx) is often a good defensive lead.
      (But avoid leading a singleton trump as your Partner will probably hold 4.)
   8. Do not lead trumps when holding J x (x) or Q x (x) , for it may cost you a trick in the trump suit you would otherwise have made.
   9. Do not switch leading from one suit to the next. Such "fishing expeditions" usually cost a trick at every switch you make.
   
   
2. Always LEAD your HIGHEST card when leading PARTNER's LONG suite.
   When Partner LEADS his long suit, SIGNAL with a high card (6 - 9) to show him that you hold an Honour in that suit. Play low when you don't.
   
   
3. Lead THROUGH Dummy's STRENGTH     and UP TO Dummy's WEAKNESS

   	Dummy (North) ♠ - A Q x ♥ - K x x ♦ - x x x ♣ - Q J x x
   West : lead Spades		East : lead Diamonds

   
   
   
4. SECOND player USUALLY plays LOW !!
   Cover an Honour with your Honour ONLY when you think it will PROMOTE a trick (the 10 or 9) in your or Partner's hand. (But when your Honour card becomes unguarded : play K from K x doubleton when you don't know where the A is.)
   (This rule also applies to the Declarer and Dummy!!!)
   
   
5. Always OVERLEAD touching Honours (Q from QJ) when LEADING a suit,
   and UNDERLEAD (J from QJ) when FOLLOWING to a trick.
   (But follow differently to DECLARER'S LEAD when it may DECEIVE him.)
   
   
6. When your HONOUR CARD in a suit sits OVER a lower Honour card (in Dummy or Declarer's hand) your FIRST PRIORITY is to CATCH that Honour if possible.
   So with K 9 x over Dummy's Q x x   >   >   play your 9 (or 10 or J) when Dummy plays low, only cover Dummy's Q with your King.
   (But with K x x you usually will have to play your K.)