Count Winners, Count Losers, Count Both

The question of whether to count winners or losers confronts every declarer and commonly pops up as a question asked of experts. The quick answer is, use the easiest count, the one that clarifies the hand best for you. It won't matter, provided your head is screwed on straight, given the inviolate number of 13 tricks per hand. If you count winners (competently), you're necessarily counting losers, and vice-versa. Unfortunately, declarers' heads are not always screwed on straight, so I suggest counting both, at least if you're analyzing a full hand at leisure to see how it might have been played better. In play, doubtless many declarers would find counting both a bit too much of a task.
I have often recommended the count of winners, since that will tend to tell you how to play the hand to bring potential winners to fruition. However, I don't recommend an inflexible policy on this matter, and will grant that the count of losers will often be the most convenient count. I only point out that when you could losers, you must count out from one hand or the other, accounting for every card in that hand. Every card must be either a winner in its own right, or go on a winner in the other hand, or be counted as loser. Can you live with that? Are there any ways of cutting the number of losers down? Answering those questions is the task before you.
But what you don't want to do is to count losers in one suit in one hand and losers in another suit in the other. That will commonly bring grief, as discussed here. So lemme give you a hand that is equally amenable to counting winners, to counting losers from the closed hand and to counting losers from dummy:

K Q J 6
K J 9 4
A 7
A 9 6
10 8 2 7 4 3
A 7 5 3 2
Q J 9 8 4 K 2
8 5 4 2 Q J 10 7
A 9 5
Q 10 8 6
10 6 5 3 Contract: 4 hearts
K 3 Opening lead: Q of diamonds

I was looking for a hand that counts out easily in each of three ways: count winners, count losers from dummy, count losers from the closed hand. And this hand certainly filled the bill. Only one wrinkle kept this hand from being the flattest board of the session -- and perhaps one of the least interesting -- and of course, that is the 4-1 split in hearts. But it proved to be a costly wrinkle to those who weren't careful, or perhaps it would be better worded, who were too complacent about knowing they'd make their contract, for the cost to those who came up with only 10 tricks was a horrendous 54 matchpoints! I've seen declarers lose less for going down in a makable contract, and quite often find that those who miss a slam, over which partners so commonly get uptight, lose far fewer matchpoints.
Well, lemme go through the counts. The easiest, I would say, would be to count from dummy. Let's see. Spades are solid. We're always losing a heart and we're always losing a diamond. We're gonna ruff that third club, no? So whatever the opening lead, let's get out the trump. Oh! West shows out on the second round. Okay, we'll hafta ruff that club before finishing with hearts. Here's one declarer who got a diamond opening lead, knocked out the A of hearts and got a club return, taken with the K. If by chance declarer is afraid of a singleton club there, which is unlikely by the odds and unlikely by virtue of the opening lead, but that's no matter, he can take a second round of trump. It doesn't matter what hand you take it in.
Now we separate the men from the boys. The boys are going to get an 18% score, the men, a 72%. You've got every heart down to the 8. And you see you're getting a 4-1 split and won't have any trump left if you simply cash out all your hearts. Just go to the A of clubs, ruff a club (you cannot be overruffed), cash the closed hand's last trump, and go to dummy with a spade. Oh, yes, we hafta chance a void in spades, don't we. Right. Draw the last trump and claim.
Or counting from the closed hand: Forget clubs. Spades are solid and offer one sluff of a diamond. The first and second rounds of diamonds are beyond our control, which means that much as we've gotta ruff a club if we count from dummy, here we've gotta lose one of the first two rounds of diamonds and ruff one diamond in dummy. Knock out the A of hearts. Had West continued with diamonds, declarer would almost surely have felt most comfortable ruffing a diamond in dummy, where also you cannot be overuffed, drawing trump and claiming.
Which brings us to a count of winners: Four spades, two clubs, one diamond and how many hearts? Well, three if we simply lead out hearts after knocking out the A. That's 10. Can we produce another trick? And the answer to that should be obvious. We can get a fourth heart winner by ruffing in one hand or the other before drawing all trump, given good communication in spades. And should.
See also You should be glad. You should be glad about these slight wrinkles offered by the cards as opposed to the simple cashing of top winners. For two reasons. First they make the game a little more interesting, wouldn't you say? Do you want a game where you just cash top winners? Or one where you're asked to use your noggin a bit? And secondly, these wrinkles (and this has to be one of the least intrusive I've seen) are what allow you to move ahead of your indifferent and careless peers. Fifty-four matchpoints for saying, I'd better get a ruff before drawing all trump?
Incidentally, I've often pointed out that the disparity in scores by virtue of missing an overtrick (or two) is directly proportional to the ease in which it (or they) can be picked up. You're not going to lose many matchpoints if an overtrick can be realized only by some criss-cross, upside-down squeeze. But you're gonna lose a lot when it's a very, very simple matter.