Most guitar players are very preoccupied with their soloing abilities, to the point of neglecting their rhythm skills. I am always surprised, for instance, by how most Blues players know how to play a solo and how few of them can play a decent rhythm that is not made just by three power chords.
The problem is, of course, that most guitar players are scared by harmony. Sure, they may know some chord patterns (after all many of us start by learning the "cowboy chords"), but they have no idea how they are built, what are the main notes in them, and more importantly how to modify them in order to be creative while playing rhythm. It's actually much easier than it sounds!
You may have seen advanced Jazz or Blues players being able to improvise using chords. It sounds impressive, but it all boils down to know how to create your own chords patterns. Of course the best way to learn this is not to start with a full-blown improvisation, but "just" by learning how to play some creative rhythm. Let's see how.
The solution to this is to learn how to use one of the most maligned interval ever: the tritone - often called "the interval of the devil" by classical music theorists and always used with extreme care. Despite its bad reputation, the tritone sounds great and is the base for most Blues and Jazz tunes out there.
The tritone, as it is expected from an interval with such reputation, is definitely a dissonant interval. To hear it, try playing an A and an Eb notes at the same time on your guitar. It's not a "nice" interval, but as we will see it's a necessary ingredient to create certain musical effects. Think of it as adding spices to your food: you don't want to add too much, but you definitely want some. And how much you put in your food depends on your taste - and the same is in music.
To learn how to "spice your music to taste" in a practical way watch the following video:
The first thing you have to do now is of course to pick up your guitar and try all this stuff. No amount of reading (or watching videos) will make up for direct experience. You will also see how it's easy to create some interesting and original harmonies by adding notes on the second or the first string as explained in the video.
By the way, I haven't mentioned this in the video, but this is a great introduction to "Jazz chords". Rather than learning all these chord shapes by heart you should see how they are built - as we have seen. There are definitely more Jazz chords out there than the ones I have shown in the video, but this will get you started. Enjoy!
Tommaso Zillio is a professional prog rock/metal guitarist and composer based in Edmonton, AB, Canada.
Tommaso is currently working on an instrumental CD, and an instructional series on fretboard visualization and exotic scales. He is your go-to guy for any and all music theory-related questions.