Rubber-Bridge Strategy

If you’re vulnerable

Overcalls should promise a better suit, more high-card points and more playing strength than non-vulnerable overcalls. Be sure you have a long, strong suit, especially if you bid at the 2-level or higher.
Preempts (opening 3-bids, 4-bids and weak jump overcalls) should be very sound. A good rule to follow is to be within two tricks of your bid — your hand should have enough playing strength that you expect to go down no more than two tricks if partner contributes little or nothing.
“Stretch” a little to bid your games. If you think you have the strength for a game contract, go ahead and bid it.

If you’re NOT vulnerable and your opponents ARE vulnerable:

Overcalls can be made with weaker hands (as few as 9 pts. at the 1-level). The better your suit, the fewer points you need to make an overcall.
Preempts can be “light” — a hand with playing strength that is within three tricks of your bid (6 playing tricks for an opening 3-bid).
If you and your partner have a good trump fit, you should compete aggressively. Don’t make it easy for your opponents to bid their game and win the rubber. The penalties for going down in your contract can be relatively small, but your loss if the opponents bid game are high — 700 points for the rubber bonus, plus the value of their game.
This is usually the only time a rubber-bridge player will consider making a sacrifice bid — a contract that you know is going down, but that you hope will cost less than the value of your opponents’ game.

If you have a partscore on:

Opening bids can be “light” (10-12 pts.) if you have a good suit. It may be important to get your suit into the auction before the opponents bid.
If you have a good trump fit, “stretch” a little to bid up to the level you need to complete the part score.
To be sure you complete your partscore, both responder and opener should be fairly conservative. Keep the auction low if you have a minimum to intermediate hand (12-16 pts. for opener, 5-12 pts. for responder). If partner opens the bidding, however, responder may want to stretch a little to get to the minimum level needed for the partscore.
If you have a stronger hand, try to show your extra power by bidding up to the level you know is “safe”, even if it’s higher than you need to bid to complete the partscore. This may be important in finding a possible slam.
Once you and partner have found a trump fit, any free bid past the level you need to complete the part score shows a hand interested in a slam. A free bid is one made over an opponent’s pass; a competitive bid is one made because the opponent’s bid pushed you a level higher.

Example: If you have 60 “on” (you need 40 to complete your game) and partner opens 1H, here are some loose guidelines responder might follow:

A single raise (1♥-2♥) or a bid of 1NT shows from 5 to 12 pts.
A jump-raise (1♥-3♥) or a jump to 2NT promises a stronger hand (13-16 “playing points”) that may make slam if partner has extra for his opening bid.
A jump to game (1♥-4♥) shows powerful trumps and a very strong hand that has excellent slam potential, even if opener has a minimum.
A jump in a new suit (1♥-3♣) shows a long, strong suit and a very powerful hand (18-19+ pts.).