1. Cover an honor with an honor only when there is a chance to promote a card in your own hand or in partner’s hand.
2. When declarer leads from touching honors (such as QJ, J10) cover the second honor unless you are short in the suit, in which case you should cover the first honor.
3. “Second hand low” is a good rule most of the time. As with almost all things in bridge, there are exceptions.
4. In suit contracts, consider leading a trump when the auction suggests that the opponents have cross-ruffing possibilities. But avoid leading a singleton trump and don’t lead trump just because you are afraid to lead something else.
5. If you’re going to be ruffing declarer’s tricks, try to ruff out his winners, not his losers. This is particularly important to the defender who plays second to the trick.
6. If dummy has a long suit that can be established, good defenders will attempt to knock out dummy’s entries before the suit can be set up.
7. Do not overruff automatically. By not doing so, you often increase the chances of developing more trump tricks. Thus with a natural trump trick, don’t necessarily overruff unless you want to gain the lead or hope to get a second ruff.
8. If you are ruffing and declarer is overruffing, you may ruff high to promote a trick for partner.
9. Do not signal unnecessarily. Instead, when discarding, pitch cards that do you no good and serve to show no interest in that suit.
10. When the opponents; bidding indicates that they have balanced hands, it’s often best to defend passively. Make safe leads and don’t break new suits. On the other hand, it generally pays to be aggressive if the bidding indicates the opponents have long suits that will produce a lot of tricks.
From It’s Just MayHem by Marilyn Hemenway, Bridge Bulletin, January 2009