I base my improvisational approach on the famous saying by Charlie Parker, " First really learn your instrument. Then, forget all that sh-t and just play!"
I take that to heart. I have worked for hours on end, year after year to really learn every note on the guitar neck. Technique wise I mainly have stressed alternate picking, but I also incorporate a good deal of slides, hammer-ons/pulloffs and sweep picking. I don't put a lot of attention on technique anymore other than to warm my fingers and hands up.
I listen to all kinds of music, especially but not limited to jazz players. I listen to harmony and progressions, attempting to work out the logic of them, as well as the lines played through these harmonies. I try to analyze the rhythmic ideas of the melodic lines as I listen. Somrtimes I don't do any of this, I just sit back and let the music affect me emotionally and spiritually.
When I solo, I kind of just reach for a melodic idea and it usually just pops out at me to shape how I want. In interacting with other players while I'm soloing, I generally respond to the drummer first, then the bass player and last to the person playing chords behind me. I try to build solos using a lot of space and bringing the solo up to a peak of excitement musically, but, I don't analytically do all this, I just let it flow and create itself. It's very helpful to sing along with my solos, audible or not, as this tends to make for a more melodic solo and adds continuity to it.
It is very important to develop a compositional flow to your solos and there is no better way to do this than to learn as many tunes as you can, and these can be jazz standards or pop tunes. Bill Evans, the great jazz pianist said he'd work on one tune for weeks and totally break it down, take it apart and learn every nuance of it. This is an excellent thing to do; learn the melody, all the harmony, work out the scales to play over the tune, re-harmonize it, play it in different keys, the works. Its very important to know where you are at all times in relation to the tune so that you can create superimposed harmonies or melodies on the tune but always be able to resolve it back to the simple changes at any time. This is probably the most important thing to work on,don't cut it short.
When I get in a musical rut, I find a solo I like by one of my favorite players( not just guitar by any means) and I either transcribe the whole solo on paper or I work out the whole solo so I can play it verbatum on my instrument. This is very valuable as it opens up your hearing for both the sounds in your head and through your ears. I have a guiding rule I follow regarding this point: there is a lag in time from when a musician hears something in his head or through his ears to the end point when he duplicates it enough to be able to execute it on his instrument, and any drill, exercise,etc which reduces this lag is theraputic musically. It is important to sort through the many approaches there are to this to hone it down to the ones that work( I have given a few here that have worked for me and I will write further articles on my website for other valuable techniques of this type). I will pass on one very specific exercise I came with: Take a simple key and a very slow tempo where you can play a simple melody in tempo without a mistake( slow it way down if you have to). Now, start a very simple melody or nursery rhyme and play it through. Before you finish it, think of another simple melody and without a break in time, go right into it when the first melody is done. Then do the same with another and another and keep going with no break in tempo- go for a half hour or more if you can. I tell you, it's murder at first! But this simple little exercise does wonders for cultivating a flow which will greatly increase your soloing in a compositional manner. Try it!
Ok, This lays out some of my ideas and approaches to improvisation. Realize you are creating new universes of sound- have fun with it!
Best, Greg Smith