I have been playing guitar for about 4 years. My biggest problem is that I don’t have a specific way to practice my improvisation. Most of the time I will be playing pieces by other musicians. I understand some basic music theories like the modes and diatonic scales, but I can't seem to apply them into my improvisation. Which makes understanding them not much of a help on my playing. I am also very weak on chords and arpeggios, for I have not much idea on how and which to practice on. Thus it makes my improvisation as dulling as just single note scale patterns most of the time. What would be the best advice for me from a great musician like you?