Most players are so busy thinking up their own moves and concentrating on their own plans that they pay little or no attention to what the opponent is doing and soon find themselves in a hopeless position.
To overcome this fault, one must remember that in chess it is not the best move that you must seek but 2 best plans - his (your opponent's) and then yours. Each time your opponent makes a move, forget your own plans for a moment and concentrate on his move. What is his plan? What does he intend to do? The earlier you become aware of your opponent's intentions, the easier will it be to meet them in the best possible way.
All plans in chess can only be based on four things:
"It is not a move, not even a best move
that you must seek, but a realizable plan."