I want to write a book search guide, but due to the nature of my work, I’m afraid the public security might come knocking. Are there any suitable channels?
General book search guides can be posted anywhere, just make sure not to teach VPN or proxy methods.
Mainly involves websites like zlib, which the public security authorities will monitor, making it quite troublesome.
Then just post it on the external network 
Platforms like Twitter; if you can access zlib, you should be able to access the external network as well.