Source: [ilink url=»http://www.acbl.org/»]2005 ACBL Bulletins[/ilink]
Using your imagination (Continuacion)
A capable defender chooses a lead by visualizing the dummy and anticipating how declarer will play. Try using your imagination as South in these lead problems.
Since you have four trumps including the ace, a forcing game may work well. Declarer has a six-card or longer spade suit, but if you force him to ruff several times, he’ll lose control and may be unable to set up and cash his side-suit tricks. A heart lead is your best chance to establish a forcing game, but since dummy has suggested heart length and declarer has shortness, lead the 
Q.
Only the lead of the Q allows the defense to succeed. If instead South leads a low heart, declarer can duck to North jack,
and North can’t continue the force effectively.
Your clubs aren’t promising enough to lead: East surely has stout clubs here. Instead, hang your hat on the diamonds despite West’s opening bid. Since the 
A Q will probably turn up in dummy, try the J or K.
Honor-trapping or «surrounding» plays are possible even on the opening lead. Only the lead of a diamond honor beats 3NT.
The opponents had a strong auction and bid both of your long suits. You must assume North has some values, otherwise the contest will be for overtricks, and it’s reasonable to try to find his long suit. If he had five spades, he might have overcalled 1
, but he would be less eager to overcall in clubs at the two level. Lead the 
10.
East’s 2NT promised a spade stopper that must be the guarded queen, but East denied four spades. Instead of leading a spade and conceding a trick, try to put North in for a spade return. If North has a minor-suit trick, he may gain the lead
in due time, but if East-West have running tricks in the minor suits, you must lead a heart. Start with the 8, denying heart strength. If North gets in, you want him to shift.