Domain: Miscellaneous (Running D&D/RPGs)
Link: Your First Adventure, Your First Town, Prepping an Adventure, Sandboxing
Person: Matt Colville
Why: Matt’s videos are really informative and his primary goal is to show that DMing is a straightforward thing that anyone can do, not something reserved for certain members of the tabletop RPG hobby. I’ve tried to pick out a few of his videos that are especially hands-on, but he has lots more which are very useful. I recommend exploring them at your leisure if you’re into TTRPGs at all.
Domain: Mathematics
Link: Teach Yourself Logic
Author(s): Peter Smith
Type: Study Guide
Why: Extremely thorough guide to logic textbooks from start to finish. Compares pros and cons of various books, tells you what parts you can skip, and identifies books with good exercises.