The current SBU course teaches strong opening two bids, but weak two bids are commonplace throughout the competitive bridge world and more appropriate for juniors.
An opening 2D, 2H, or 2S opening bid shows:
Juniors are typically more aggressive than most players in opening weak twos, but whatever your style it is important to disclose it on your system card. Your style should take into account the vulnerability and position.
If you are non-vulnerable against vulnerable, then you can be very aggressive because the opponents will want to bid their game rather than take a penalty.
When non-vulnerable against non-vulnerable, you can be more aggressive with hearts and diamonds and more conservative with spades. This is because pre-empting with spades is more likely to leave the opponents no option but to double you rather than find their fit.
When vulnerable against vulnerable, you should be conservative especially when relatively balanced, as going down will score poorly especially if there is no game available.
When vulnerable against non-vulnerable, you should be conservative as any penalty will be the opponent’s best bet.
You can more aggressive with more distribution.
You can be aggressive in first position, as it is 2:1 odds that your opponents have a good hand rather than your partner.
You should be conservative in second position. It is 50:50 that your partner has the good hand at the table (and pre-empting makes it more difficult for him) and your left-hand opponent knows his partner has a poor hand and is more likely to make the right decision.
In third position, you can do anything you like as partner has a bad hand.
In fourth position, you do not open a weak two bid as you would pass. So the best idea is for 2D, 2H, and 2S to show an intermediate two bids, 9-12 points, no interest in game, but trying to win the partscore.
S xx H AQ10xxx D xx C xxx A classic weak 2H opener | S Kx H 109xxxx Pass. A poor suit, points outside the long suit. |
S xxxx Open 2H, do not worry about holding four cards in the other major. | S xx Open 2D, do not worry about the 4-card major. |
S xx H KJxxx D xxxxx C x Only open 2H when first position AND non-vulnerable against vulnerable. Pass at all other vulnerabilities and positions. | S A10xxxx H xxx D xxx C x Open 2S when non-vulnerable, pass when vulnerable. This is a minimum hand. |
As opener has defined their hand reasonably well, responder should only introduce their own suits if they may be a better fit. Responder should also remember that opener is limited in high-card points and has a hand that will probably play better in their suit than others. So there is little point in bidding unless game is possible or you wish to pre-empt/sacrifice.
A new suit is forcing and shows 5+ cards and at least game invitational values (15+ points). Responder will support with a fit, rebid their suit without a fit with minimum values, and make a descriptive bid without support but maximum values (this may occasionally be a feature for no trump, like Kxx in a side suit, rather than a long second suit).
A 2NT response is forcing and asks opener to describe their hand. It normally promises game invitational values with or without a fit: it tends to deny their own good suit.
Opener then: