Here’s a bidding guide for deciding whether to double an opponent’s contract. It’s called the Rule of Nine. It works as follows. Start with the number of cards you hold in opponent’s suit. Add any honors you hold in the suit. Finally, add the level of the contract. If the total is nine or higher, double to your heart’s content.
I was reminded about the rule when I made an inauspicious double in a contract that looked beatable. I was sitting North and dealing, with no one vulnerable:
Don’t help your opponents. That’s simple enough in concept but more complex in action.
• Don’t take a finesse for your opponents. Here you have the lead early in a 4♠ contract:
Dummy: ♠ A J 10 5
You: ♠ 9 8 7
Whatever you do, don’t play spades, hoping partner has the king. Here are the other hands:
Partner: ♠ Q 2
Declarer: ♠ K 6 4 3
Do you see what happens? If you’d let well enough alone, declarer probably would take the spade finesse through dummy, losing to the queen. By leading spades yourself, you give declarer an extra trick.
Pre-empts can be fun for bidders and hellish for opponents. Here’s perhaps the most satisfying interference bid I’ve seen. In an OK Bridge game I played with Paul Laliberte, East -West were vulnerable and South was dealing:
NORTH (Kaplan)
♠️ 4
♥️ J 8 7 6
♦️ 9 6 5
♣️ K J 9 7 3