I wonder if you might consider coughing up some money for an actual book. First off, I am not recommending and have not read the book I'm about to mention and there may be others - this is just the first one that seemed really on topic. Okay?
With that disclaimer.... there is a book called WordPress Plugin Development (Beginner's Guide), by Vladimir Prelovac (looks like it just came out in January)
The reason I mention this is because after hemming and hawing for ages, I finally coughed up the money and bought John Van Dyck's Pro Drupal Development and by the middle of chapter 2 I was kicking myself for not having bought it the second it came out. It is just so much better - both the writing and the format - than the online resources. The amount of time I could have saved myself would have been immense. Before I even reached the halfway point, the book had saved me so much time already with an ongoing project that I felt I had easily been repaid the purchase price.
Obviously, that's a review for another book and it has nothing to do with your situation, just to say that a good book, that is well-thought out, will just save you so much time over the online resources in my experience.
It's funny, but I never felt any need to buy a book on PHP, for example, because it's just syntax and if you know a little programming, learning PHP is simple. But the internals of some of the CMS systems are complex and not at all intuitive (not illogical either, just very difficult to reverse engineer by looking at code).
So that's not a real answer, but hopefully a useful suggestion. If you do buy the book, it would be great if you came back and let us know whether or not it was as helpful to you as Pro Drupal Development has been to me.
