This new textbook from Soren Bjornstad is highly recommended for learning TiddlyWiki. The presentation and design are also a first class example of using TiddlyWiki.
From the site:
Grok TiddlyWiki is a textbook that helps you build a deep, lasting understanding of and proficiency with TiddlyWiki through a combination of detailed explanations, practical exercises, and spaced-repetition reviews of prompts called takeaways.