First, you have participated in some calligraphy competitions and won prizes. This is the best way.
Second, you have teachers from the Calligraphy Association, that is, you can learn from them and let them introduce you. This is the best introduction method, that is, someone in the calligraphy association introduced you to join the club.
Third, you can bring your own works to the county and city calligraphy associations, let them read the words, and then join.
If you want to join, the best way is to be introduced. Finally, you must make sure your handwriting is good. Of course, hobbies are the main thing. Generally speaking, all counties and cities are good, the calligraphy association above the provincial level is the most difficult, and the China Calligraphy Association is even more difficult.