Octaves are a simple and effective way to enhance a basic guitar riff. Secondary guitar tracks can really bring out the energy in a song and add to it’s melodic movement. I am using the A minor scale as well as A Dorian scale to create this melody.
Here are some Modes you can experiment with of this A5 G5 D5 C5 progression;
A minor- A B C D E F G A
A Dorian- A B C D E F# G A
A Phrygian- A Bb C D E F G A
A Locrian- A Bb C D Eb F G A