Improvisation is a gift that you can work for. I'm at the point in my playing where I think it's finally coming together for me, but I have a long way to go in my technical execution. I have the following recommendations:
1) Record yourself playing lead guitar. Play it back and see what you'd like to change. Your perception playing is not the same as listening, and this serves as a good check.
2) Have a pocket full of simple chops you know by heart and can throw in at anytime.
3) Know the importance of the one and the five. They get the job done, as Billy Gibbons says. Especially the one, according to BB King. Be ready to go up or down an octave on the one, and you can't go wrong if you go to the one on the chord change.
4) Play every note like it was meant to be played, even if it is wrong.
Slide up one fret on any wrong note and it will be a right note.
5) know the importance of a pause. When you're running out of gas, take a pause and come back in.
6) A few well placed notes are often better than a hand full of busy notes that just fit the scale. I used to think it sounded cool to throw a lot of notes at the listeners, but some of them don't like that. Others do. As a listener I'm listening for quality and connectivity more than quantity. "Too many notes" becomes confusing to me as a listener.
7) Pick a couple of easier songs and learn the lead-guitar note-for-note. I haven't done enough of this myself. It's terribly repetitive, but most great lead guitarists have done this and will tell you so.
I could say more. I'm not at the point where I can improvise at will but I'm working on it. The thing that's probably most important is a fluency to your playing, where an idea is connected. You can know some good chops but they have to connect to each other.
I guess a book can be written on this subject. I've often wondered what the lead guitar player's thought process is.
I'm finding out it comes more from a familiarity with the instrument, the song material, and acting on certain feelings that come out, even if I'm not producing the notes I really intended - the feeling will take me to the right place on the fretboard. The resolution sounds like it is a planned and connected idea because of where it ends up rather than where it started. I'm still programming my fingers to act on what I feel. It's pretty satisfying when I can hit the note I was looking for, and build on that feeling. The audience likes to hear that too. It's coming from within, like a non-verbal language.
I hope I'm not being too esoteric, and I have a long long way to go in my performance.
