Central strokes can't be mastered in a short time, and some people can't master them well for several years. Only by knowing the essentials and practicing for a long time can we master them. Chinese painting is the basic skill of calligraphers, and it is also one of the symbols of calligraphy level.
The key to hitting the ball by the center is very simple. First of all, when writing, the pen must always be perpendicular to the paper. No matter how you write or move, you can't skew. You can only change the height (calligraphy is called lifting pressure), speed (calligraphy is called slowing) and turning (calligraphy is called turning). Secondly, when writing, the direction of the pen should follow the principle of thinking left before thinking right and thinking down first. The purpose is to make the nib always run in the center of the stroke, which is the essence of the center pen.