Concentrate on the opening lead for a few seconds so you'll remember it later. Decide what it tells you about the leader's length or strength in that suit.
Mentally review the bidding. If one of your opponents has bid, try to come up with a general picture of his point-count and his length in the suit bid.
For most suit contracts, your general plan should be:
1 - Count your losers. Decide which ones can be disposed of or turned into winners (by trumping, by finessing or by discarding them on a side suit).For most notrump contracts, your general plan should be:
2 - If your plan calls for trumping one or more of your losers in the short-trump hand (usually dummy), do that before you lead trumps -- even if you have to give up tricks to set up the trumping position.
3 - Next, lead out your trumps, counting as the opponents follow to each trick. (This will usually be your best approach if you have good honor strength and/or length in one or more of the outside suits.)
4 - Attack your longest side suit. Give up your losers early.
5 - Last, cash honors in your short suits.
1 - Count your winners. If you don't have enough top tricks to make your contract, decide which suit offers you the best chance of creating more winners.
2 - Attack that suit first (it will usually be your longest side suit). Give up the tricks you have to lose early.
3 - Stick with one suit at a time. Keep leading it until you've established your tricks (counting the defenders' cards as you go), then cash your winners in the suit. When you move to a different suit, start counting again.
4 - Last, cash honors in your short suits.
Don't lead unsupported aces (Ax, Axx, Axxx) unless it's the suit partner has bid.
When in doubt about what to lead, lead the fourth-best card in your longest suit. Leading from length is the "standard" lead to a notrump contract, and it's often the safest lead to a suit contract.
Count cards and points as you play. Use clues from the bidding, the opening lead and the play to try to come up with a mental picture of partner's or declarer's hand.
Think ahead, and be ready for critical plays. Indecision will often tell declarer what you hold in a suit, so try to decide in advance which card you'll play when declarer leads a suit toward or from dummy.
Use defensive signals to help partner during the play:
When discarding or following suit, signal with the highest card possible in a suit you want partner to lead. Play a low card if you have no interest in the suit.
Consider playing 3NT instead of 5C of 5D when you have the strength for game, but your only fit is in a minor suit.
If you have length in the opponent's suit and are in doubt about what to bid, pass. Don't show your problem by thinking too long about what to do.
Keep the bidding simple. If you have a fit for partner's major, always raise.
If you have a fit for partner's suit, "stretch" to raise, especially in a competitive auction. If you have extra trumps (one more than you need for an 8-card fit), feel free to compete to the 3-level if the opponents bid over your 2-level partscore.
Always assume partner has a minimum until he tells you otherwise. A minimum range is 13-15 pts. if partner opened the bidding; 6-9 pts. if he responded to your opening bid.
If you have a minimum hand (13-15 pts. for opener, 6-9 or 10 pts. for responder), keep the bidding low until you find a fit. Don't go past the one-level unless:
You're raising partner's suit.
You're rebidding your own long suit.
If you know you have 25 combined points, jump to game in your suit or notrump. Don't give partner a chance to pass.
If you have an invitational hand (16-18 pts. if you're opener; 10-12 pts. if you're responder) and you think you and partner might have 25+ points, make your bid one level higher than necessary. This usually means you'll freely take the auction to 2NT or 3 of your suit.