My personal blog has a long long set of articles on technical topics if you're so inclined. If you go to some of the older ones you can basically see me learning OOP and SOLID before your eyes, and then trying to apply it to Drupal. It's an odd history. :-)
In particular:
https://www.garfieldtech.com/topics/web-development/php
https://www.garfieldtech.com/blog-topics/architecture
I hope some of those prove helpful/useful.
I will have a look :) thanks will you be posting some tips and tricks on here too?
¯_(ツ)_/¯ I'm making this up as I go.
Me too haha