LEARNING CENTER

2 (or 3). This auction calls for a trump lead. You can imagine dummy coming down with a singleton spade (give or take), so this will cut down on ruffs. 

3 (or 4). Same reasoning as the last deal: declarer is going to try to ruff spades in the short hand (dummy). 

A. What happened to "never lead unsupported aces?" There's an exception to every rule. Here, you need to get tricks quickly and looking at dummy is your best bet. Against a preempt, it's generally ok to lead aggressively as the king is unlikely to be with declarer. 

A. Another unsupported ace! If you guess a suit to lead before dummy comes down, you deserve to see the dummy show up with AKQ of that suit with declarer discarding (void) in that suit. Playing the A doesn't give up a trick (you know your Q will be a trick later), but allows you to pick a sensible suit to lead at trick two. 

2. Dummy's clubs could be running after trumps are drawn. We need to get our tricks quickly and diamonds is our best bet. 

K. We're not looking for safety when dummy could come down with AKQxxx of a suit. We need tricks, fast. Diamonds is our best bet as we can set up a diamond trick on our own or catch partner with the ace (or ace of spades). 

2. Leading from a king against a small slam is often the way to defeat the contract (when possible). You don't expect to hit partner's ace, but maybe partner has the queen of clubs and an outside ace. Again we expect a long suit in dummy and need to attack.