Reddit reviews Harmony and Theory: Essential Concepts Series (Essential Concepts (Musicians Institute).)

Music Theory is one part of what you're talking about, but you're also talking about ear training.

Knowing your scales, and chords, is one thing, but knowing what they sound like when you hear other people playing them is another. Ideally you would want to get to a place in your playing where you can hear the notes, or lines before you play them, and then just play them. That's a very high level of musicianship that comes after lots of dedication.

One of the best things you can do for a "shortcut" is learn to hear certain chord changes. Once you can hear how the roots of the chords are moving around, (eg: I-IV-V, or iii - vi - ii - V) then you can work on hearing what tonality they are. (eg: Major, Minor, Diminished, Augmented)

For theory books I really enjoy this one: http://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910

For Ear Training I enjoy: http://www.amazon.com/Ultimate-Ear-Training-Guitar-Bass/dp/0793581567

This was the first introduction that made things start clicking for me http://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910

A great theory book for guitarists (starting from the basics) is this. Definitely nothing in there about "polytonal rhythms" (whatever they might be, they certainly ain't "fundamental")!

You'll see it goes as far as "chord substution and reharmonization", but by that point I would be starting to take it a little less seriously, and maybe moving on to something more in depth. (Those "jazz theories" can get controversial.)

Of similar level - less guitar-based - is this. This is more like an exercise book, with the information in each chapter followed by test questions, with answers in the back. (Just one of the answers is wrong in my very old edition... hopefully fixed now.)

I really recommend at least two sources when reading music theory. Every author has their own angle, and their own readership in mind. It may be that one book (or website) clicks with you, but the others will always fill in gaps here and there, and what's not clear in one may be clear in another. When all sources agree, you can be sure you've got good info. When they don't ... more research needed!

Best general theory website is probably https://www.musictheory.net/lessons - very well organised, right from the basics. It will "walk you through" if you resist skipping pages and take it steadily, step by step, in order. You may need the first book above (or something similar) to help translate notation to the guitar.

Don't forget to always play the stuff on the guitar as you're reading. If you don't know how to play it, don't try learning it. musictheory.net provides sounds, so you can at least hear the stuff, but best if you can play it yourself.

Justin's Practical Music Theory PDF is an excellent resource.

If you'd like to take things further, and as Justin recommend on the site, I'd also highly recommend MI's Harmony and Theory:

https://www.amazon.com/gp/aw/d/0793579910/ref=mp_s_a_1_1?ie=UTF8&qid=1486590104&sr=8-1&pi=AC_SX236_SY340_QL65&keywords=harmony+and+theory&dpPl=1&dpID=617snwalTUL&ref=plSrch

I do NOT want to discourage you - but I don't think there is a quick way to learn music thory. It takes time and practice and experience. But it is definitely possible! Just think of it as a language : the written dot on the staff corresponds to a pitch - just like an a corresponds to the sound a. It must become natural. So I guess my advice is to read a LOT of music. Every day, if possible, and of different styles (classical, modern etc.) If you want your pieces to really sound original, you have to know what others have written before you - and learn from their craft.
That being said, I think there is a good deal of great books about harmony that you can read to guide your development, I will list a few here :

• Arnold Schoenberg : Theory of Harmony (A bit tedious to read, but with great many examples)
  
• Arnold Schoenberg : Fundamentals of Musical Composition This one is great but a bit advanced; I suggest you read it when you master the harmony basics.
  
• Carl Schroeder & Keith Wyatt : Harmony and Theory: A Comprehensive Source for All Musicians This one is recommended, but I didn't read it myself.
  
• Barbara Wharram : Elementary Rudiments of Music. This one I grew up with. Very straightforward and clear.
  
  Might I suggest that you play all the examples and excercies at the piano so that you train your ear to hear what you see.
  
  Also, you might want to contact a piano teacher and take lessons for a year... or two. Technique is a great part of playing, and is very difficult to learn on his own.
  
  Sorry for the long post, but I love music and want to help a fellow player. Also, sorry for potentialy awkward sentences, english is not my first language.
  
  Hope this helps!

I've got this one- http://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910

and it's pretty good.

Also, check out http://www.musictheory.net and http://www.teoria.com , they're both fantastic resources.

Have fun and good luck!

Start with pentatonic and blues scales, learn about chord subs, the basic 7th chords (dominant, diminshed, maj, min etc), minor scales and modes on them etc. Here's some string-specific books in my local library that i thougth good:

• http://www.berkleepress.com/catalog/product?product_id=1219764
  
  
• Waller, "Past the Print http://www.amazon.com/Mel-Past-Print-Julianna-Waller/dp/0786607564/
  
  
• Julie Lieberman wrote a few book on jazz/blues/folk styles: http://www.amazon.com/Improvising-Violin-Completely-Revised-Lieberman/dp/B0017S4802/
  
  --------
  
  here's a couple good ones, non-strings specific (helps to have a piano/MIDI controller/guitar and DAW to make chord backing tracks
  
  
• Edly's Music Theory for Practical people: http://www.edly.com/mtfpp.html
  
  
• http://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910
  
  
• Chad Johnson, Guitarist guide to scales over chords: http://www.amazon.com/Guitarists-Chords-The-Foundation-Melodic-Soloing/dp/1423483219
  
  

Well many people bash others who tout their knowledge of theory. But that really is the next step. Either find a good book or better yet a good instructor.

check out the table of contents of this book using amazon's "look inside feature"

i'd have them do a chapter or so of this book every week:

http://www.amazon.com/gp/product/0793579910/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

http://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910/ref=sr_1_1?ie=UTF8&qid=1374293971&sr=8-1&keywords=musicians+institute+theory

this book is amazing.

This is my favorite theory book: https://www.amazon.com/Harmony-Theory-Comprehensive-Musicians-Essential/dp/0793579910