Here is a quick excerpt, this book is filled to the brim with these gems.
> The final twist of the Twitter anecdote: now that approach 2 is robustly implemented,Twitter is moving to a hybrid of both approaches. Most users’ tweets continue to be fanned out to home timelines at the time when they are posted, but a small number of users with a very large number of followers (i.e., celebrities) are excepted from this fan-out. Tweets from any celebrities that a user may follow are fetched separately and merged with that user’s home timeline when it is read, like in approach 1. This hybrid approach is able to deliver consistently good performance.
Approach 1 is a global collection of tweets, the tweets are discovered and merged in that order.
Approach 2 involves posting a tweet from each user into each follower's timeline, with a cache similar to how a mailbox would work.
The Architecture of Open Source Applications series is a good one for leaning how to build production applications and you can read it online. The chapter on Scalable Web Architecture is a must-read.
Clean Code: A Handbook of Agile Software Craftsmanship  is a great book on writing and reading code.
Similarly, Clean Architecture: A Craftsman's Guide to Software Structure and Design  is, no surprise, a book on organizing and architecting software.
Designing Data-Intensive Applications  may be overkill for your situation, but it's a good read to get an idea about how large scale applications function.
The Architecture of Open Source Applications  is a fantastic free resource that walks through how many applications are built. As another comment mentioned, reading code and understanding how other programs are built are great ways to build your "how to do things" repertoire.
Finally, I'd also recommend taking some classes. I started as a self-taught developer, but I've since taken classes both in-person and online that have been a tremendous help. There are many available for free online, and if in-person classes work better for you (motivation, support, resources, etc), definitely go that route. They're a fantastic way to grow.