| Soloing on 1 string
Hey man, Hope the books are serving you well. In regards to soloing on one string, the first step to this is to practice your scales and arpeggios on one string. For example, take the G string, play all of your arpeggios: major 7, Dom.7, minor 7, minor7 b5, diminished 7, min.(maj.7)and also practice scale types on one string. When you practice scales on one string this reinforces that you think of notes. This may not always be the case when we play scales on multiple strings as sometimes we may get locked into the finger pattern used to play the scale. When you play scales (music) on one string , this is thought of as playing scales in a “horizontal” fashion, as opposed to the “vertical” approach to playing on several strings. Pat Metheny once said that when in high school he would practice entire melodies of tunes and play improvisations all on one or sometimes two strings. I find that when you play this way, and Pat is evidence of this, that the music tends to be more lyrical and not about “chops” and in can help you play more musically. Does this mean that you can’t play musically if you don’t play on one string? Absolutely not! But I do think that if a player adopts this way of thinking into their repertoire of approaches to improvisation, that this will help you expand your musical ideas. So, in a nutshell, try to practice all of your chord and scale forms on first one, then two strings. Then play with a metronome or drum machine and try to create melodies while playing on one or two strings. Let me know how it goes.
Peace,
Dave | 
