A similar topic was started recently here: Can I customize the welcome message shown when creating a new topic based on the chosen tag or category?
I don’t think there’s a built-in way to do exactly what you want today.
Topic templates (as suggested above) are probably the closest fit with developing some kind of #theme-component or something.
One option would be to include some thing in HTML comments in the topic template so it wouldn’t show up in the post even if the user doesn’t remove it, e.g.:
<!--
some tips for new topics in #category
- foo
- bar
- baz
-->