Leads after a preempt by Matthias Huberschwiller

A: 2♠ - North's hand can be of various forms: Strong, or Weak with a good fit.
You need to set up quick tricks, because South may have discards on dummy's Diamonds or Clubs. By leading a small Spade, you aim to take your tricks before it's too late.

Your result so far:

A: 2♥ - You have the majority of the points. Where are your opponents going to make their tricks?

Ruffs. You need to prevent them, by leading a trump.

Your result so far:

A: 2♠ - The declarer will soon have a lot of tricks by setting up the Clubs. You need to choose the most promising suit to lead: You may have only one shot at defeating the contract.
Spades look promising, as you will set them up if your partner has the Ace or the Queen.

Your result so far:

A: 2♥ - What a collection of bad leads. You need to pick the least bad one. A trump is excluded, since your partner may have an honor, and declarer no Spades in dummy.
You need to try and set up tricks, and leading an unsupported Ace is too dangerous. In Hearts you may set up a trick if your partner has an honor. Even if he has nothing, the Ace and Queen of Hearts will probably be in dummy, so you won't give a trick away.

Your result so far:

A: A♠ - You know exactly what's in declarer's hand: A solid 7-card minor. If you give away the lead, you might no get it back until declarer wins his contract.

You need to check which suit you have to play, and by leading the Ace of Spades you'll get to see the dummy. It would be too bad if you were to lead a Heart, and dummy came down with the Ace-King of Hearts and nothing else.

Your result so far: