To play defense at the bridge table can be though. It is quite often a little drop of guess in the early part of the defense that decide whether you succeed or not.
Lets try this hand from a teamgame:
You are sitting east. 1NT showed 15-17 and 2 spades was natural. North first made a negative double then raised to game as all other reasonable persons would do.
West led the jack of spades, dummy contribute with the deuce. How do you plan this defense?
When the hand came up during a regional team event east ruffed followed by the queen of clubs. That was not the best effort he could do, it gave declarer the contract when the cards looked like this
South took the ace of clubs, pulled trumps with the ace and king followed by the ace, king and queen of spades discarding a club for dummy. The defense only took a diamond and a club together with the ruff.
When east ruffed the lead, it worked as a ruff and sluff for declarer who could pull the trump in two rounds then discard a club looser on the bid spades.
East had to discard a club or a diamond on the lead. Declarer then can only make 9 tricks losing a trump, a diamond and two clubs.