When you are declarer,  wait to play to the opening lead until you have planned how you will play the hand. Are you playing IMPs, rubber bridge or matchpoints?  Are you doing well or badly?  What do you know about the opponents’ hands from the bidding? Consider what is your best line of play depending on what type  of game you are playing, and your situation.  If it’s not rubber bridge, keep in mind how well you are doing. How will your line of play go if you have favorable breaks? How will you can cope with bad ones? . You should then play the hand  as quickly as possible. Your opponents may have neglected to have ask themselves similar questions plus neither of them will know all the resources their side possess. By your

 thinking out possible contingencies beforehand,  either defender may err by making a play that is inferior. If your side is defending, the one who is sitting third should pause before playing to the trick and ask herself similar questions.