Bidding : Pass (N) - 1S (S) - 3S (N) - 4S (S)
North having passed initially, jump raises his Partner's suit, showing a maximum pass (11-12 pts) and trump support.

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

Declarer (S) counts 4 possible losers in the combined hands : at least one in the trump suit, two losers in Diamonds and one in Clubs.
Declarer can get rid of one loser in Diamonds by ruffing his third Diamond in Dummy. He must do this immediately and before drawing the enemy trumps (otherwise he may not have trumps left in Dummy to ruff his third Diamond).

Declarer Play
Ruffing a loser in Dummy before drawing trumps - Defence leading trumps to prevent Dummy from ruffing
Declarer wins the opening lead with the Diamond Ace and, at trick 2, leads another Diamond. West wins with the Queen, and realising what Declarer has in mind, leads a small trump at trick 3. East wins with the Ace and leads another trump (trick 4), won in Dummy with the Spade Jack.
A small Club from Dummy (trick 5) to Declarer's Ace brings the lead back to Declarer. He now plays his last Diamond (trick 6) which he ruffs in Dummy with the remaining Spade Queen. A second small Club from Dummy returns the lead to Declarer's hand, who then proceeds to draw the last remaining enemy trump.
He finally cashes Dummy's two Heart winners for a total of 10 tricks.

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

Bidding : Pass (E) - 1C (W) - 2NT (E) - 3NT (W)
East after his initial pass jump bids 2NT after Partner's 1C opening. This shows a maximum pass (11-12 pts) a balanced hand with no 4-card major.

Opening Lead : Spade 5 (S) = 4th from the top

Declarer (E) counts 6 sure winners : four Aces plus the Kings of Spades and Clubs. Extra tricks may be found in Hearts and Clubs.

Declarer Play
Direct finesse against the Queen   -   Indirect finesse against the King
The opening Spade lead provides a lucky break for Declarer winning the trick with his 10 (Always play low in Dummy in this situation.) At trick 2 the Club Jack is lead for a direct finesse of the Queen. It holds and 4 tricks are collected in the Clubs.
At trick 6 a small Heart is lead from Dummy to Declarer's Ace, then (trick 7) a small Heart back for an indirect finesse against the Heart King. This works. With proper play Declarer ends up winning 11 tricks in total, 3 in Spades, 3 in Hearts, 1 in Diamonds and 4 in Clubs.

Score = 40 + 4 x 30 trick pts + 300 bonus pts = 460 pts total

Bidding : Pass (S) - 1C (N) - 1S (S) - 1NT (N) - 2NT (S) - 3NT (N)

South's response of 1S shows 6-12 points and a 4+ card Spade suit. Although he has a maximum pass he should not bid 2S, as this would show a 5-card Heart suit. South raises North's 1NT bid to 2NT, inviting him to go to Game with 14-15 points, or pass with a minimum 12-13 points.
(North, being the third player to bid, could have opened with 12 pts.)

Opening Lead : 10 of Hearts (E) = top of a solid sequence

Declarer (N) counts 6 sure winners : Ace of Spades, A K Q J of Hearts and the Ace of Diamonds. Two more winners can come from the Spade suit and at least one more in Clubs.

Declarer Play
Ignoring a possible finesse   -   Indirect finesse against the Queen
Declarer should win the first trick in his hand with the Heart Queen, saving a sure entry in Dummy (the Heart Jack).
He should not bother to try the finesse in Spades against the King. He can only finesse once and therefore is likely to loose a Spade trick anyway. He therefore (at trick 2) leads the Ace of Spades, followed by the Queen (trick 3) which is taken by East's King.
East (trick 4) switches to Diamond leading a small card. Dummy plays low (Declarer holds 10 and 9) and West wins the trick with the King. Returning a Diamond would place East's Queen in an unbeatable finesse situation. Therefore West leads (trick 5) a safe Heart, won by Dummy with the Jack. The two Spade winners (J and 10) are now cashed in Dummy, with Declarer discarding two small Clubs.

At trick 8 Dummy's last Heart is won by Declarer's King. He cashes his last remaining Heart winner (the Ace), discarding a small Club in Dummy, then plays the Diamond 10 for a direct finesse against the Queen which holds. Dummy's Diamond Ace and one Club trick will complete Declarer's total to 10 tricks.

Score = 40 + 3 x 30 trick pts + 300 bonus pts = 430 pts total

Bidding : Pass (W) - 1C (E) - 2H (W) - 4H (E)
West with a maximum Pass (count length points !!) and a 6-card Heart suit responds with 2H. East has excellent trump support and therefore raises to Game.

Opening Lead : King of Diamonds (N) = top of a solid sequence

Declarer (W) counts 5 possible losers two in Hearts and three in Diamonds. Two Diamond losers can easily be discarded on Dummy's Clubs or by ruffing in Dummy. With luck he will catch at least one of the enemy's trump winners.

Declarer Play
Direct double finesse against K and Q
North wins the first trick. Seeing that Dummy is now out of Diamonds he switches to Spades which is won by Declarer's Ace.
At trick 3 Declarer leads a Diamond, ruffed by Dummy. Then the trump Jack is lead from Dummy. South drops the King, Declarer wins with the Ace. He concedes the trump Queen to North but wins all remaining tricks, 11 in total.

Score = 5 x 30 trick pts + 300 bonus pts = 450 pts total