Bidding : 1C (N) - 1D - 1S (N) - 2H * - 2NT (N) - 3NT

* = 4th suit forcing. With the Heart stoppers but weak North replies 2NT.

LTC : 7 + 6 = 13 losers.

Opening Lead : 10 of Diamonds. A lead through Dummy's strength. Avoid a Heart lead away from A Q, for North has promised a stopper, surely the K.

Declarer (N) counts 7 sure winners : 3 in Spades and 2 each Diamonds and Clubs.

Declarer Play
4th suit forcing bid   -   Leading through Dummy's strength   -   Avoidance play
Dummy wins the opening lead with the Diamond Ace.
One or two additional tricks can come from the Club suit, but Declarer must take the direct finesse from Dummy. This will avoid West gaining the lead, who otherwise could have lead through Declarer's K J 6 Heart holding.
The Club Queen is onside so 9 tricks are assured. After cashing the four Club tricks Declarer can now return to Dummy via the Spade King and safely take the indirect Heart finesse to his Jack. East wins with the Queen and leads another Diamond. Dummy's King wins the trick, but Declarer can now only cash his two remaining Spade winners for a total of 9 trick. Attempting another Heart finesse would be suicide.

Note : By not leading Hearts North has deprived Declarer from making a single trick in that suit. An opening lead of Hearts would have given Declarer an overtrick on a platter!

Score = 40 + 2 x 30 pts + 300 bonus pts = 400 pts

Bidding - 1C (E) - 1H - 1S (E) - 2D* - 2H (E) - 4H

* = 4th suit forcing bid. East gives delayed 3-card support for Partner's Heart suit.

LTC : 7 + 7 = 14 losers

Opening Lead : King of Diamonds (N), to "have a look at Dummy".

Declarer counts 3 or 4 possible losers : one each in Spades and Diamonds, and one or two in Hearts.

Declarer Play
4th suit forcing bid   -   Only drawing opponents' losing trumps   -   Ruffing finesse
After seeing the singleton Diamond in Dummy, North (having won the first trick with his Diamond King) switches to the 10 of Clubs (leading through Dummy's strength). Dummy wins the trick with the Ace. Then leads a small trump to Declarer's Ace of Hearts.
Declarer can pursue several ploys, but North's opening lead clearly has marked him with ♦ A K.
Declarer therefore leads his ♦Q for a ruffing finesse against North's Ace. If North plays the Ace, it is ruffed in Dummy (making Declarer's Jack a winner). If North plays low a small Spade is discarded in Dummy, and Declarer then leads the ♦J which is ruffed in Dummy.
Dummy's last remaining trump is now lead to Declarer's King. The opponents' trumps break 2-3, leaving them with one trump winner (which Declarer should not draw).
Declarer now plays the King of Spades, then leads a small Spade to Dummy's Jack for an indirect finesse against the Queen. This trick is won by South.
Declarer eventually loses one more trick to North's trump Jack, but wins 10 tricks in all.

Score = 4 x 30 trick pts + 300 bonus pts = 420 pts

Bidding : 1C (S) - 1D - 1S (S) - 2H* - 3C (S) - 4S

* = 4th suit forcing. By rebidding his own suit, South denies a Heart stopper and 3-card support for Partner's suit.
3NT is therefore clearly not on, but North with a strong hand and two Honours in Spades feels it is worthwhile to go for 4S, even with the unfavourable 4-3 trump fit.

LTC : 7 + 7 = 14 losers

Opening Lead : King of Hearts (W) = top of a solid sequence

Declarer counts 3 possible loser (two in Hearts and one in Diamonds), provided the trumps do not break worse than 4-2 and he manages not to loose trump control.

Declarer Play
4th suit forcing -   refusing to ruff.
This is a simple game which so easily can go wrong.
West wins the first trick with his ♥K, and follows on with leading the ♥Q which wins, and then his ♥J. If Declarer ruffs this trick in his own hand he is a dead duck!
Instead Declarer discards the losing Diamond in his hand. If West now leads yet another Heart, it can be ruffed (high!) in Dummy.
But West has run out of Hearts and switches to a Diamond, won by Dummy's Ace. Declarer now draw 4 rounds of trumps and cashes his 5 Club winners, safely home with 10 tricks.

Score = 4 x 30 trick pts + 300 bonus pts = 420 pts

Bidding : 1C (W) - 1D - 1H (W) - 1S* - 3S (W) - 4S

* = A natural response, promising 4+ Spades and 6+ points.

Opening Lead : Queen of Clubs (S) = top of interrupted sequence

LTC = 5 + 7 = 12 losers

Declarer (E) counts 3 possible loser : one or two in the trump suit and one in Diamonds. But with only very small trumps (apart from the A an K) and an ominous unbalanced distributions all round, things can easily go wrong!

Declarer Play
Forcing opponents to ruff
Declarer wins the first trick with his Club Ace in Dummy and takes stock.
In view of the unbalanced distribution in both his own and Dummy's hand it is rather likely that opponents' trumps are split 4-1 (or perhaps even worse). The opponents hold the five highest cards below Dummy's King, so they always will make 2 tricks if the split is 4-1.
Therefore if Declarer first draws two rounds of trumps and then forces out the ♦A in order to set up his Diamond winners he may well go down. If the four trumps and ♦A are in the same hand (as is the case here with S), the opponent ((S) will win with the Ace, draw two rounds of trumps and cash in the remaining Club tricks.

To avoid this Declarer (at trick 2) draws one round of trumps with Dummy's Ace and then leads Dummy's small Diamond to his King. South wins with the Ace and continues with ♣J, which is ruffed in Declarer's hand. Declarer (at trick 5) leads the ♦Q, which wins the trick.

At trick 6 the situation as show here, and Declarer continues with his ♦J on which (regardless what South does) discards Dummy's last remaining Club.
If South ruffs trick 6, then leads trump, Dummy will win the trick with the King, leads Hearst to Declarer's Ace, who then leads the ♦10.

If South at trick 7 leads a Club or a Heart instead, Declarer wins the trick in his hand and also ♦10.
No matter what the Opponents try, the contract is always secured.
The critical play here is to use a side suite to draw opponent's dangerous trumps.

Score = 4 x 30 trick pts + 500 bonus pts = 620 pts