Watch the Raising Hell online guitar lesson by Jeff McErlain from Play in the Style of Billy Gibbons
What we have here is a Gm blues. What makes a minor blues? Easy - it's that standard 12 bar form but all our chords are minor. In this case we have Gm, Cm, and Dm. The reason I chose to show you this example is Billy's use of the thumb over the top of the neck to play the root. This is a very useful technique that I can't imagine playing guitar without. Not only does it free up the fingers on the left hand to play some nice embellishments, see Jimi Hendrix, it provides a particular sound. As you notice, the thumb comes over the neck enough to fret the root and MUTE the 5th string. It is essential that that string not ring out as it will most definitely kill your buzz dude. By omitting the 5th string from the chord we get a nice open sound not clouded by the power chord element we get if playing a full barre chord. In this particular groove the thumb bass note helps separate the bass note - chord- bass note- chord riff much more easily than standard fretting.