Some players are accused of "thinking too much." There's no such thing as thinking too much. The problem is knowing when to do the thinking.
The rule is simple. You think between games and between points. When the point is about to start, you stop thinking. You blank your mind out and just let go. It is thinking during the point that causes a person to freeze up with uncertainty, often labeled as choking. Once the point begins, the conscious you is not controlling play; it is your subconscious that takes over.
Some players can't stop thinking when play begins, and try to consciously control their shots. That rare;u ends well. Others are able to let go and let the subconscious take over, but don't think between points either. That rarely ends well tactically.
Think about what actually happens when you play. Suppose your opponent gives you a backspin. Do you consciously say to yourself, "Ah, the ball has backspin, I must aim up this much to return it." Hopefully not! Instead, after facing backspins for a while--and probably messing up at the start, and telling yourself you need to aim up against backspin--your subconscious gets the message, learns just how much to hit up against varying degrees of backspin, and it becomes habit. The same is true of tactics.
How can you play tactics during the point if you aren't thinking during the point? The answer is if you spend enough time thinking about tactics, it too will get absorbed by your subconscious. If you decide you need to loop a deep serve to the opponent's wide forehand, you don't wait until you see a deep serve, and tell yourself, "Ah, a deep serve. I should loop it to the wide forehand." Instead, if you remind yourself regularly what you need to do, the subconscious will learn to get the message, and you'll do it automatically.