By Andrew Robson 
Courtesy of AndrewBobson.co.uk
Some years ago a drink company sponsored bridge tips. Mine was this, ‘If a preemptor leads his suit, play him for a singleton trump’.
The most common shape for a (three level) preemptor is 7321 (about four times as common as 7222). He’ll presumably lead his singleton – unless it’s in trumps.
Exercise: Make 4 ♠ after West opens 3 ♥ then leads ♥ A and another.
Win ♥ K and, playing West for a singleton spade, cash ♠ K. Assuming West follows low,
continue with ♠ J, playing East for ♠ Q97x. Say East covers ♠ J with ♠ Q. You win ♠ A as West
discards. You cross to ♣ A, lead 4 ♠ to (♠ 7 and) ♠ 8, cash ♠ 10 felling ♠ 9 and run minor-suit winners. Game made.
On our main deal (below), West’s ♠ Q opening lead tells you a huge amount. Within the spade suit, he would not lead from ♠ A, so East has ♠ A; and moreover with West having seven spades, East’s ♠ A is bare. Further, West chose to lead a spade rather than the singleton that most hands with seven-card suits contain: he probably has a singleton trump.
The first move is to play dummy’s ♠ 4, expecting East’s ♠ A to ‘beat air’. It duly does and East follows with ♣ AK then a hopeful ♣ Q. You ruff and must negotiate trumps for no loser.
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Weak hand (err yes) with a decent seven-card suit.
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Take-out, but (very) marginal. North is asking partner to bid at the four-level holding a weak notrump hand without four cards in the other major. Dubious – but at least partner will have a good idea of the opposing hands from the bidding.
Playing West for a singleton heart, the best way to broach the suit is to cross to dummy and run ♥ J. This will be successful unless West’s singleton is ♥ Q: ie four times out of five.
You lead to ♦ A and advance ♥ J. East covers with ♥ Q and you win ♥ K, West following with ♥ 3. You cross to ♦ K and lead ♥ 2, covering East’s ♥ 6 with ♥ 7, as expected West discarding. You cross to ♦ Q lead ♥ 4 to ♥ 8 and ♥ 9, cash ♥ A felling ♥ 10, then cross to ♠ K to dump ♠ 6 on ♦ J. 10 tricks and game made.