Why do I hit the ball out?
The most common reason is the strings and your racket, the frame can lose tension 7 to 10% immediately after being strung. Strings, when you play with the racket will then also goes down in tension which makes the racket more trampoline-ish, that’s why balls end up going long. the other reason or common one is the angle of the racket face is open. The players don’t understand mechanically why the ball goes out. The challenge is in the players stroke. The player requires proper form and that requires a tennis lesson.