regarding the improv in general, once you can understand the system, the biggest part of the challenge is out of the way. For myself, when i learned (almost entirely self taught) i found the easiest way to learn how to start utilizing the system is to really pick an artist that excels at that sort of play. People often mention the very flashy player like eric johnson and vai, but also vaughan is an excellent artist to listen to and emulate to really start understanding how an improv playing style is achieved. Another group to listen to, somewhat more contemporary would be coheed and cambria...or at least their live recordings, which incorporate massive improv sections. Just hearing it done alone can give a lot of insight on how the note progression can work. Again, these are just things that worked for me, so dont take it as a tried and true method. Good luck!