Stumbling to Defeat

K 9 7 5
J 10 9 8 7
A K 6
6
Q J 6 8 3
Q 3 K 6 4
10 9 7 3 J 8 5 4
A K J 8 10 7 4 2
A 10 4 2
A 5 2
Q 2 Contract: 4 spades
Q 9 5 3 Opening lead: various

Four declarers bit the dust on this rather simple hand, two of 'em without any self-ranking, two telling us they're advanced players, one a GLM, the other a SLM, which I take to be a Gold Life Master and Silver Life Master respectively. How can we best count out the hand?
It would seem apparent that you'd do well to count out from dummy's holding. We see that we hafta lose a spade, barring luck, which includes the bad luck of a 4-1 split. We're always losing a club, and one heart if the double hook works. To be sure, you'd come to the same conclusion if you counted out from the closed hand, to wit: we're losing a spade, a heart on the double hook, no diamonds, and of the four clubs, we're gonna lose one, throw two on the long hearts and ruff one. Either way, you've gotta get your trump out (well, two rounds), take the double hook in hearts and get back to cash the long hearts.
So any way you slice it, we've gotta be very careful of our entries. We need three to dummy, and by chance we have three, to wit: K of spades, the second round of diamonds and a club ruff, after losing a club. Oh, technically, we have two entries in diamonds, but no, you can't afford to overtake the Q. We just hafta make use of every entry very carefully. Thus:
Win the opening diamond lead with the Q, take two rounds of trump, ending in dummy, and start your double hook in hearts. West wins, and it's no problem if he cashes the high trump. Indeed, I'd prefer that he did, for we'll gonna hafta knock it out if he doesn't. Suppose he wins that heart trick, cashes the high trump, then a high club and continues with a low club. Not being able to see his hand, we ruff that second round of clubs. Which means that we have no more trump in dummy, and if the second half of the heart double finesse doesn't work, we're down a couple.
No matter. You must continue with that viable line to your contract. If it fizzles, well, so it fizzles. But I've seen a lot more contracts kicked away by people who chickened out at the sight of risk than contracts saved by getting skeered. In the event just outlined above, we ruff the second round of clubs, continued with hearts, now the second lead holding, as West follows. (Had West shown out, meaning we'd finessed into a stiff Q and East started with 3 guards to the K, that also would doom us.) We now cash the A of hearts, dropping the K, and laying a low diamond on the table say, "Board's good."
Here's what those advanced Life Masters did: Diamond to the Q, diamond to the A (!), low club (!!!). You don't wanna spend that diamond entry so early, and you'll lose the club soon enough and don't need to do it for the defense when your task is to set up your winners, no? But worse was to come. For upon winning the club lead, West continued diamonds, declarer sluffing a heart! Yikes! Now he can't take the double hook! He has only one guard to the A and needs two!
Could declarer have still made his contract when West was in on the club lead? Yes, it looks to me as though he could, since West didn't wipe out an entry on the diamond lead. Declarer was in effect given back an entry (since he couldn't lead diamonds himself), and could've effected his double finesse by sluffing a club on the K of diamonds and leading a heart from dummy. West wins and plays the A of clubs (he won the club lead earlier with the J), declarer ruffing, continues the double finesse and cashes the A of hearts.
West can ruff and play another high club, but that still leaves dummy with two trump, the same as West, so declarer can cash the A of spades and go back to the K and claim.
The second declarer fizzled out early: A of clubs opening lead, diamond riding to the Q, spade to the K, J of hearts, uncovered, up A! This is bad. C'mon. You've gotta have the courage of your convictions. East shouldn't covered, to begin with. Don't cover the first of equals (by and large) and dummy has five of 'em (equals). And don't chicken out on your natural and necessary finesses. That's not the road to a winning game.