sharyn,a place to start with bass runs,are the individual notes of the chord,plus passing notes second and sixth,for a g chord this would be g a b d e,this is the pentatonic major scale,for a g minor chord it would be g a bflat d e.,this is the pentatonic minor scale.sometimes replacing the third[the b in my example]with a c[sus4?]works well too,the best thing is experiment and if youlike the sound ,keep it.