I have always (well at least the last 35 years or so) been a fan of strategy in pool.
Strategy in 8-ball consists of several mechanisms, some dependent on the skill level of your opponent.
In 8-ball it is alost always wise* to roll the OB towards the pocket at as slow a speed as you can. If you miss, you leave an obstruction to your opponent, and an easy shot for yourself next time. If your opponent has a ball near a pocket, blocking your OB and you have no other reasonable shot, bank your OB in front of his ball obstructing the pocket and (at least) making forward progress.
Look for two way shots, shots where you can make your OB and leave the CB where a: you have a reasonable to good next shot and b: where your opponent has no reasonable shot if you miss. If you get good at two way shots, your opponent won't even know you are playing defensive.
If you are left with no reasonable shot, play a good safety: a: that leave the CB where no reasonable shot can be played by your opponent, b: where the comission of your safety advances your position by 1: solving a problem, 2: moving a ball to an easier subsequent shot position, 3: blocking a pocket or 4: critical ball of the opponent. Your opponent might have an OB covered by two of your balls, blocking all but a small angle of approach. You can roll one of your own balls to make it impossible for him to touch this ball first (without a jump). Thus, he cannot run out (also works on 8-ball). Make sure you are playing under the 3 consecutive fouls=game rules.
And then, even the occasional deliberate foul advances your cause and hinders your opponents cause.
(*) and almost always improper in 9-ball.