A video-tutorial demonstrating how you can move a lot of the routing registration in Slim3, into the controllers, thus simplifying your codebase if you have a lot of routes.
Learn how to use UUIDs in MySQL for your table IDs, rather than using auto_increment.
A lightning talk on UUIDs from the maintainer of the ramsey/UUID package library for PHP.
A talk made by Macro Pivetta on "Doctrice ORM Good Practices and Tricks".
Learn how to include your package within itself for testing and not have to keep pushing the code and composer updating.
Request certificates from LetsEncrypt after having proven that you own the domain.