Free online LaTeX course by John Lees-Miller, co-founder of Overleaf.
Part 1: The Basics
Part 2: Structured Documents & More
Part 3: Not Just Papers: Presentations & More
Video tutorials - a series of 21 short videos by Dr. Vincent Knight of Cardiff University.
Topics 1-5:
Collaboration tools
Every project you create has a secret link. Just send it to your co-authors, and they can review, comment and edit. Overleaf synchronizes changes from all authors, so everyone always has the latest version. More advanced tools include protected projects and integration with Git.
Collaborate online and offline with Overleaf and Git
Protected projects with Overleaf Pro