Counting 1 Suit ...
Keeping track of the cards you, your partner and the opponents as they are played. When you are in a suit contract trumps is just a simple count. If you are in a notrump contract, the first suit you count is the usually one that offers you the greatest number of potential tricks often your longest combined suit - and it's usually the suit you lead first
(1) Count up from the number of cards you and dummy hold in the suit. If you have a total of 8 cards in a suit in your hand and dummy, you would start your count at 8 and then mentally count up to 13 as the opponents play their cards in the suit. If both opponents follow to the first lead of the suit, you would count 9-10, then 11-12 on the next trick. Subtracting the last number from 13 will tell you how many cards the opponents still hold in the suit.
(2) Count down from the number of cards that are missing. With an 8-card fit, you would start your count at 5 and then mentally count down to 0. If both opponents follow to your first lead of the suit, you would count 5-4. The next number in the sequence is the number of cards the opponents still hold.
Counting 2 Suits...
Once you have mastered counting one suit, you’ll want to move on to figuring the distribution of two or more suits. To do this successfully, you need:
The ability to count to 13 at least twice (4 times, is even better).
Memory skills, which can be developed with practice. A basic knowledge of the meanings of bids, leads and defensive signals.
Technical skills – knowing how to use “discovery plays” and other techniques that help you collect clues about each player’s distribution.
Concentration. You have to put some energy into counting. Pay attention to every trick and change your picture of the unseen hands as you collect new clues.
Counting 3 Suits....
This may involve counting points or the number of cards in an opponent’s hand. This may seem difficult but it often involves no more than counting to thirteen.
General tips for counting:
Memorize the common patterns of the 13 cards in a suit -- 4432, 4333, 4441, 5332, 5431, 6322, 7321, etc. (Note that all the patterns of four numbers fall into one of two even-odd combinations: three even numbers and one odd, or three odds and one even.) Drill yourself on the patterns and become so familiar with them that you won't even have to think once you get a partial count. If you discover that each opponent has 4 cards in a suit and you hold 2 cards, you won't need to do any arithmetic to know that partner holds 3. The 4432 pattern will instantly pop into your head. Commit it to memory by repeating the pattern in your head (for example: 3-5-3-2, or 35-32). Do the same with your own hand. Later in the play, if you can't remember how many cards have been played in a suit, you can often reconstruct the play and figure out how many times the suit has been led by recalling your mental picture of the number of cards you and dummy originally held in the suit. Practice, makes perfect. It will take time and lots of practice before you can process all the information available and make the right conclusions. You can speed your progress by making a concentrated effort to count at least one or two suits on every deal you play, even on those where it appears you can't affect the result. Early in the play, try to decide which suits are critical and concentrate on counting just those suits. As a defender, try to start your count with the suit you or partner led, then move on to figuring the distribution of one of the declaring sides longer fits.