Bd1 starts with a difficuly one with 5  out of 5 different contracts.

North should pass.

South bids a normal 1♥ .

West has a difficult bid. Cannot double due to terrible shape. Some may try a risky 1NT to show values. Probably best to pass andsee what happens.

North could pass, in which case East can do what is known as a balancing double. South has nothing more to add.

West can now bid 3NT which is a good contract.

Some Norths instead of passing the 1♥  from partner may jump to 2♠  which can buy the contract. Now days many people play this as weak and showing at least a 6 card suit. This is for two reasons. 1. because he has passed, but if he had not passed, 1♠ is forcing.

Another difficult hand.

The question is how to get to a good game contract.

Passes around to North will be normal.

North bids 1♥ 

South then has a difficult bid. 2♥, 1NT or 2NT or 2♣ ?

The hand shape 4333 is the worst possible shape but you have 10 HCPS?

2♥ s may be the wrong contract if North has 4 and could get passed.

1NT is also likely to kill the auction.

2NT is better and show a maximum for the pass. It could be too high, but partner bid with a poor 10 or 11 without ♠ s he would pass the hand out.

So 2♣ will encourage partner to bid.

North has 6 loser hand but is too weak to jump to 3♥ s, so bids 2♥ s.

South can then raise to 3 and North finds the easy bid to 4♥ .

Many will pass before game.

West opens with 1♥  planning to bid NTs to show his HCPs and shape.

North doubles. Not a prefect shape but OK.

East can bid 2 or 3♥ s. 3♥ s is pre-emptive and is justified by bidding to the level of the fit and is probably the better bid.

South may bid 3♠ s for the same reason, assuming partner has 4♠ s and they have 9 spades so should bid 3♠ s (6+3).

A key tool on evaluating your hand if you find a trump fit is Losing Trick Count. Have a look.

West has to decide between bidding 4♥ s as he has extra values or doubling 3♠ s. As partner might be competing etc.4♥ s is probably best.

West opens 1♥ . In position 3 some parterships agree to pre-empt with a wider point range as it is unlikely you will be in game.

South overcalls 1♠.

West can bid 2♥ s and North will show values with 3♣ s. East will bid 3 or probably 4♥ s and South will bid 4♠ s. Some Easts may bid 5♥ s which with this vulnerability is dangerous.

North opens with 1♥ .

south has a choice with his 11 HCPs. With a weaker hand he would prefer to bid 1♠  as he may not get another chance to bid. But with the 11HCPs he can bid 2♣ s and bid 2♠ s if North rebids 2♥ s. Which happens. There are enough HCPs to end up in 2NT.

North can then bid 3♥ s to show his shape which South can raise to 4♥ s.

A very good weak  2♠ opening.

North with 4♠ s cannot double.

East knows that North / South have the balance of points. His 9 plus the 5-9 that west opened with. So if he passes South has an easy double over 2♠ s, but will find it difficult over 3♠S.

If South doubles over 2♠ s, North will find the optimal contract for them of 3♦ s.

With 8 quick tricks West can open 2♣ and East responds 2♦ with 7HCPs. With 8+ HCPs you could bid a 5+ card suit. Though as often opener will bid 2NT to show a balanced 23-24 and you can either bid Stayman or do a transfer to a better contract - it is often better to bid 2♦ as a relay.

However this time West will bid 2♠ s as ♦ are short and he can easily show his 5/4♠ ♥ 

East having more than 4 HCPs can bid 3♣ s.

West shows his shape by bidding 3♥ s and East with a good ♦ stop can bid 3NT. Which will normally be the best contract. 

West opens a weak 2♥ .

North has 21 HCPs, with West showing 5-9 HCPs, an average of 7 gives 28 HCPs for West and North. So East and South will have 12 and an average of 6 each. So North / South should have enough for game.

so North can bid 3NT though with a risk of having just one stop.

1NT by West, North with 16 HCPs can double (15-18). As this double is normally for penalties you do not alert - you alert bids that the opposition would not expect to be the ‘norm’.

East knows that with only 12-14 plus 4 they will not make 1NT, so how to escape?

There are numerous systems so include this link to a common simple wriggle used by many.

1NT doubled and Wriggle