A plan. A good chess player thinks about the plan he or she has formulated to attack the opponent. Too many players play without a plan on what to do and how to do it. They just move pieces with no thought about setting up the opponent for the kill. This requires thinking several moves ahead of the one about to be made. For example, a good player might notice that the opponent's King is in danger of a back rank mate, but that a piece of the opponent blocks the way. The good player figures out a way to capture or get the blocking piece to move out of the way. The plan might require making at least two moves to do this but if successful in getting the blocking piece out of the way, the opponent's King is mated.