Modern tennis is very easy. You just focus on finding the ball really well, with no pace yet on your racquet, and then, while touching the ball with the racquet, pull and turn your hand to feel the ball across the strings.
Even though the racquet may be fairly loose, you are actually forcefully accelerating with an inward force (towards oneself), rotating and bending the arm up to the finish, with the butt of the racquet ending pointing to the direction you just created on the ball.
One caution note: this is much easier done open stance, where the playing hand is closer to the ball and the help of the body occurs more naturally.
This is an interesting and barely recognized way of playing with an extended feel and a pronounced topspin on the ball that increases its power, both linearly and rotationally.
While widely accepted in the best tennis centers in Europe, plus some in Asia and South America as well, most USA “experts” have fought this knowledge for years, contending the stroke goes forward through the ball and coming across only when it leaves the strings. The “experts” most likely don’t realize that increasing contact time increases confidence, control and also power effectively, and that this is the main reason for success at the top level of the modern game.
Top pros do something with the hand on contact with the ball that they can’t explain themselves other that showing the particular motion, although they are aware that this is one of the biggest secrets of their success. Why? Probably because they focus on feel, rather than thinking.
How do you apply that yourself to your own game? Aware that you don’t devote as much time to the practice of this sport as the top performers, just exaggerate this torquing movement not with force, which could hurt your arm, but with a decisive change of direction of effort when you strike the ball. Pull, rather than push.
In a funny way, you could think of stroking forward to find the ball, backwards when you are in contact with the ball. Meanwhile, the racquet that started under the ball, and now moving upwards to impart topspin, will accelerate very markedly up and across derived from the change of direction with little effort on your part.
With my best wishes,