I consider diseased thinking to be an unofficial part of the sequence on words (of which "37 ways words can be wrong" is the hub). It gives an example for how words can influence our thinking that is not contrived, practical, not obvious and important. It's a nice example of clear thinking.
One thing that could help new users dive into Less Wrong would be to make some reading recommendations based on reading difficulty. (I'm including some things not hosted on LessWrong.com when they're very LessWrong-ish and written by leading LessWrong authors.) For example:
For everyone