My Swivel presentation all about marketing worldbuilding:
More links coming later, but for now:
AnswerThePublic.com is the standard for questions and interests research.
Buzzsumo question search is kick ass
Canva is my new favorite fancy-schmancy charts tool
Grammarly will save you from philsophy massacres
My original article about worldbuilding
Practical typography is an amazing primer for making great places.