Weakest link

A player's position is only as good as the weakest potential link in their best connection across the board.

Thus, with each move you should attempt to either improve your weakest link or make your opponent's weakest link even weaker. A move which does both is a strong move.

For example, in the position below the cell f6 is the weakest point in Red's best connection across the board. It is also the weakest link in the Blue's best connection across the board. Thus, the player whose turn it is to move would be wise to play at f6. In fact, whoever plays next has a forced win after playing f6.