Riffs can be played against virtually any chord progression (i.e., not just 12 bar Blues). The following example illustrates a one bar riff played against the Am, Gm and Fm chords.
This riff uses notes from a minor scale, because it is played against minor chords. Minor scales are discussed in more detail in Lesson 14 and in Appendix Two . To maintain a smooth sound in this riff, use the fingering as indicated and use alternate picking.