Once you open 1m, it is very likely that your partner will respond and you will have another chance to describe your hand. Remember, bidding is all about conveying information that will help your partnership reach the right contract. Therefore, a good guideline if you are not sure what to do is to think “what does my partner already know about my hand?” Once you pinpoint what you have not described yet that your partner may find useful, try to think about how to make a bid that conveys that information.
Opener has a lot of choices, in order of priority (in most cases):
Raising responder’s major suit
Bidding a new suit at the 1 or 2 level
Rebidding the original suit
We will look at each one of these ideas.
Raising Responder’s Major Suit
As noted in the “Responding to 1m Opening” section, it is extremely important for the partnership to be able to identify major suit fits. Thus, if you have a fit, you must notify your partner immediately by raising the major suit. Since partner’s bid shows at least 4 cards in the major, if you also have 4 (note with more than 4 you should have opened the major), you have found a fit. Otherwise, try another option.
If a fit is indeed found, opener should reevaluate their hand using support points (add in shortness points) and raise based on the following chart (in support points):
Minimum 13-15 points Raise to 2-level
Medium (invite) 16-18 points Raise to 3-level
Maximum (Game) 19+ points Raise to game
You open 1♦, partner bids 1♠.
Bid 3♠. You have 14 HCP + 3 shortness point for the doubleton heart, so raise to the 3-level. You are not quite strong enough to bid game yourself, but you have too much extras for a minimum 2S response.
Bidding a New Suit at the 1-level
With no fit for responder, opener should look to see if they have a secondary suit they have not told partner about yet. Opener should bid this suit at the 1-level or 2-level, depending on which is lower.
No fit for responder
Can be with a minimum hand
You open 1♣, partner bids 1♥.
Bid 1♠. You can continue to search for a fit by announcing you have 4 spades. Partner could have 4 spades in addition to 4 hearts.
With a balanced hand and no support, 3NT is a likely possibility so it is a good idea to tell partner you have a balanced hand (implies no second suit).
Balanced hand (with unbalanced, would bid suit)
No second suit (4+ cards) to bid at 1-level
Rebid of 1NT shows 12-14
Rebid of 2NT shows 18-19
Notice that the gaps 15-17 and 20-21 are missing because those hands would open 1NT or 2NT directly.
You open 1♦ , partner bids 1♥.
Bid 1NT. You have a balanced hand worth 13 points (12 HCP + 1 length point). With no fit in hearts and no second suit, bid 1NT.
Rebidding your suit
With a 6+ card minor, that is a suit worth rebidding and telling your partner about! Note that it is still preferable to raise partner’s suit or bid a secondary suit because that is more descriptive.
Therefore, our requirements are simple:
6+ in the suit
No second suit to bid
No support for partner
You open 1♦, partner bids 1♠.
With 6 diamonds and an unbalanced hand, rebid 2♦.