Watch the Difficult To Grasp: Rhythm 1 online guitar lesson by Andy Aledort from Jam Night Vol. 3
This part kicks off with a vamp over the one chord, Bb, so when faced with "sitting on" one chord for an extensive length of time, it's effective to devise a lick that can be repeated and also elaborated upon while not sounding too obtrusive and getting in the way of the vocals. I begin with a series of two- and three-note shapes fretted on the G and B strings, thirds apart, and based on the Bb mixolydian scale (Bb C D Eb F G Ab), starting with a Bb triad--D F Bb--with the third, D, as the lowest note. I then switch to Eb/Bb, sounded y simply barring across the D, G and B strings at the eighth fret, and I can then keep the Bb on the bottom to play a Bb7 voicing of (low to high) Bb F Ab. Notice the 16th-note syncopated strumming throughout, as fret-hand finger pressure is released to sound muted dead-string accents between the chordal hits.