There's always a point when I start to learn something new where I start to see the patterns in the system--the connections in what I'm learning which helps me to form the neural pathways in my brain and start to learn faster.
There's one book in particular relating to music that really helped me to "get" scales and chords. Written for the piano, it's called How to Play Popular Piano in 10 Easy Lessons, by Norman Monath. It's a slim book, but it was revolutionary in my approach to piano, and all melodic music in general.
The book teaches just enough music theory for you to be able to learn half a dozen chords, then modify those chords into about 30 total chords, using set rules. This is sooo much easier than memorizing 30 separate chords.
Also, the biggest thing I got from this book was the simple act of how to play a major scale starting on any note. It's all about thinking of notes as half steps and whole steps. Once I internalized the pattern, I could play major scales on piano, and, I just learned yesterday, the guitar.
It really bugs me that most music lessons, whether online, in a book, or with a real live person, really lack any element of music theory or practical knowledge.