Hand No. 3 26-Mar Dealer South EW Vul.
S   J1085 West North East South
H   KJ10 1C
D   K4 1D 1S 2D 3S
C   10843 No 4S End
S   K7 S   642 Question: what should East lead?
H   Q8742 H   A953
D   QJ1093 D   A82 Most players know it's bad to lead away from an
C   Q C   652 Ace against a Trump contract.  They take that
to mean they should lead the Ace.  But that is
S   AQ93 equally bad, even in partner's suit, unless you
H   6 have Ace and King. 
D   765
C   AKJ97 On this hand, at eight tables North played the
hand in a Spade contract.  At seven tables
East led an Ace and ten tricks were made. 
But if East manages to resist the temptation to lead an Ace, either a Club or Spade would
defeat the contract.
Just one East led a Club.  Result - 2 Down and a well deserved top for East West.
Note - at the 5 or 6 level it may sometimes be OK. To lead an Ace.