I guess the most important thing is that your hands are not stable enough.
The reason for instability may be that you practice less. The other is that the posture is not correct.
If you are a beginner, it is recommended to put your wrist on your pillow, that is, when you sit and write.
Remember to press the hook when holding the pen, and the palm should be hollow.
Hang up the pen and don't tilt it. Remembering the strokes in the middle can reduce your stroke mistakes.
In addition, the ink should be adjusted.
Calligraphy is a difficult art to learn. Good luck.