A few suggestions.
First - go out and get yourself a copy of Mick Goodrick's
The Advancing Guitarist. It's the best book on the subject I've ever seen.
Second - you don't know even half the chord progressions and theory you need to know. Which is a good thing. Keep learning harmony, but remember that when you're on the gig you need to leave the theory at home. While you're at it, learn arpeggios, and learn them well. They are your friends!
Third - (this is the most important point I've got) if you want to learn how to solo,
listen to great soloists, and steal from them! The single most useful thing you will ever do to learn how to solo (or play in any way, really) is to transcribe other people's stuff. Now, please note that I did NOT say to find someone else's transcription; I said transcribe it yourself! Find something you like, sit down, and figure out every damn note they played. And write it out - that is an essential part of transcription, because then you can look at the chords they are playing a line over, and figure out how they go together. Which brings me to...
Four - don't just transcribe the solo - transcribe the rhythm section too. It doesn't matter if you know every lick Pat Martino ever played if you don't know where he played it - so dig into those chord progressions.
Five - (and this is another big one) do NOT just listen to guitar players. The fact is, most jazz guitar players are playing shit that is 20 years behind what the horn guys are doing (please note that I said MOST). Guitar players have too many other things to worry about. We have to know chords, and how to comp, and we can actually get the occasional gig in a pop band that actually pays money. Occasionally, we even get to spend time with this thing called a woman! All most horn players have to do is sit around their crappy little apartments and practice improvisation
D). Needless to say, they tend to be pretty good at it. So learn from their anti-social habits, and transcribe horn solos. Piano players tend to have a hard time getting woman too, so transcribe their solos too (
). From a more serious point of view, horn players and piano players have a very different perspective on soloing due to the nature of their instruments. You will never be able to duplicate their lines exactly, but that's not the point. You can get ideas from them, and then it is up to you to figure out where to go from there.
Sixth - work on your articulation. A lot of jazz guitar players, particularly young ones, tend to spend a lot of time picking every note. Listen to those horn players I mentioned, and you will find they are not doing anything of the sort. Slides, hammer-ons, pull-offs, bends - all that shit is your friend, and a big part of what makes a solo expressive. My favorite Jazz guitarist is probably Pat Metheny, and his articulation is just slippery. He may or may not be as fast as Mike Stern or Pat Martino, but his playing is a whole hell of a lot more interesting to listen to than Stern's constant be-bop scales or Martino's machine gun sixteenth notes. And it's all because of that slipperiness.
Finally - learning to solo in Jazz is a lifetime endeavor. So is comping. Hell, so is just listening to the shit. But you will NEVER learn anything until you get out and start playing it with other people, preferably in front of an audience (OK, OK, it's jazz - on a stage, there probably won't be an audience!).
And though I couched some of this in (bad) humor, it's still all true. Or at least, I think so. So does every great jazz guitar player I know, and I know more than a few.
Oh yeah, also, jazz has enough tenor sax players - try to keep your ego in check. There is nothing worse than an arrogant jazz musician who looks down on what everyone else is doing simply because it isn't
Jazz.
Light
"Cowards can never be moral."
M.K. Gandhi
You can probably guess I'm not a fan of the safe scale approach, because I think the soloist should drive the changes and not be driven by them.
