Spade Heart  Diamond Club
Bidding after a 2C opening bid
Bidding with a Balanced Positive hand after a 2♣ opening bid
Bidding with a Balanced Positive hand after a 2♣ opening bid

No Trump contracts on the hand detailed above made 11 or 12 tricks by North and South depending on the lead.  Nearly all pairs opened their strongest bid 2♣ or 2 and one pair of brave (?) souls finally ventured 6NT but were defeated by the A♠ lead and a Heart switch.

The pair that benefited most had a bid in their armoury to get to the best contract.  After an opening 2♣ by South, North with a fair balanced positive bid (at least an Ace and a King, or three Kings)chose to bid 2 as either a Negative bid or possible "Waiting Bid".  South was now able to confirm his Diamond suit with 3.  North set the suit with 4 and South advanced with a fine cue bid of 5♣, suggesting a Diamond slam, not forcing to one!  Note that this cue bid denied the Aces of s and ♠s but showed at least something "very nice" in both suits that had been bypassed.

Holding the A, North, thinking that South may have a possible singleton in and at least the K or KQ in Spades, now chose to give nothing more away and bid a simple 6.  East led the 10 but slam was cold on any lead.

North won in Dummy, drew trumps, led a to the Ace and played a ♠ towards the K in dummy, which held.  Now able to lead a ♣ to the K and play another ♠ towards Q, East took his Ace and 12 tricks were there.  Note, if East ducked the ♠ a second time, North could make 13 tricks by ruffing ♠s with his remaining small s.

6 making gave N/S all the match points for an outright top.  Also, North got to play with one of the weakest suits you can hold as trumps!

Tip - 7  CONSIDER USING 2 AS EITHER A NEGATIVE BID OR A "WAITING BID". This can be shown with your second bid.  Here when North raises Diamonds he must have a positive.