From “Take All Your Chances” by Eddie Kantar

How should you attack these hands? If you are declaring a notrump contract, count your sure tricks. If you don’t have enough to make the contract (you won’t!) look for some way to develop that missing trick or tricks. If you see at least two lines of play to secure those extra tricks, stay alive! Give yourself a chance to take both lines. At trump contracts counting losers and sure tricks is the way to go. If the total doesn’t come to 13, count your cards.

There are many hands where more than one line of play exists to make your contract. If you select the best percentage line, your chance of making the hand increases, but if you don’t … But why take the worst of it? The idea is to take the line of play, which if it doesn’t work, still allows you to take the other line, and there ever may even be a third line! This is called “staying alive”; in other words, avoid putting all of your eggs in one basket!

Unfortunately, but realistically, there will be hands where you have to decide immediately between several lines of play. The opponents have forced your hand and there is no time to try one line and then switch to another if the first doesn’t work. Now it helps to know a bit about percentages or the odds.

The bidding will be given and explained. Use the bidding as a guide in the play.

Assume IMP scoring. Play to make and do not worry about overtricks or undertricks.

West North East South
4
Pass 4NT Pass 5
Pass 6 Pass Pass
Pass

After you open 4, partner uses Blackwood to make sure you have an ace and sets you down in 6. Opening lead: ♣K: Plan the play.
You have two possible losers, a spade and a diamond, and you have two chances to get rid of at least one of them.

You can take the diamond finesse. If it wins, you make an overtrick, if it loses you are down one as the ♠A is the setting trick. Alternatively, you can lead up to the ♠K first. If West has the ace, you won’t need the diamond finesse as a diamond goes off on the ♠K assuming West goes up with the ace. If West plays low, the king wins and you can take the diamond finesse for an overtrick. If East tops the ♠K with the ace, you still have the diamond finesse available.

Tip:
When two lines of play are available, take the one that gives you a chance (keeps you alive) to use the other if the first fails. Expect this theme (“staying alive”) to appear time and again in these hands, just as at the table. Lead up to the ♠K to stay alive.
Percentage-wise, if you lead up to the ♠K first and that doesn’t work and then take the diamond finesse, you have a 75% chance of making the hand (one of two finesses).
If you put all of your eggs in the diamond finesse basket you have only have a 50% chance of making the hand.