1) optional paste
According to one's personal preference for calligraphy, one can be selected from excellent Chinese characters and block letters. The copybooks for reference are as follows:
Jiucheng Palace or Huadu Temple in Tang Dynasty
(Tang) Yan Zhenqing's "Yan Bei" or "Ma Gu Xian Tan Ji"
(Tang) Liu Gongquan's Mysterious Tower Monument
(Yuan) Zhao Mengfu's Danba Monument
2) Fine replication
After selecting the copybook, cover the words on the copybook with tissue paper and carefully trace the outline of each word with a signature pen or ballpoint pen. In this process, pay attention to the structure of each word and the stroke shape of the pen. Describe it in two or three hundred words like this, and you will feel something.
3) Blank copy
Close the copybook, tick the words described by memory, and then open the copybook to find out the differences from the original text, and make up and perfect it.
4) Practice more.
Practice makes perfect is a cliche, but it is really not difficult to write hollow characters. Keep practicing according to the above methods, and you should be able to write a good double hook word soon.
I wish you success and a happy new year!