You should both tactically and strategically develop your game. What does this mean?
First, let's define these terms. Tactical thinking is what you do when you are looking to win now. Strategic thinking is what you do when you are looking to develop in the long run. You need both.
Let's assume you have a big weakness in your game - say, a weak blocking game. You could tactically find ways to hide this weakness, which is something you should do when needed in an important match. But the great majority of matches are practice matches where you should be developing your game. So instead, you should tactically realize you have a big weakness in your game, your blocking, and strategically play and practice to develop this weakness into a strength. But it starts with tactically understanding what parts of your game need strategic developing - both weakness and strengths, where the goal of the latter is to make them overpowering strengths by making them stronger and by developing more ways to get it into play.
But if you always are playing strategically, you never develop the tactical skills to win a given match. The result is you might have a better game than an opponent, but you lose because the other player is better tactically. What this means is that if you only think strategically, your tactical skills will suffer.
So you must find a balance. Decide in advance which matches you will focus on the strategic, and which ones on the tactical. Or sometimes play strategically until it's close, and then try to win tactically. Or the reverse, which many players neglect to do - when it's close in a practice match, if you always play tactically, you won't developed the deep-rooted confidence in the shots you are trying to develop, so sometimes try to win with those shots, even if it means occasionally - or often, at first - losing a match that you might have won.