Jazz improvisation performance. You’ve been preparing. You have mastered your instrument with long tones, scales, and exercises. You have worked on general knowledge of music theory, chords, and the relationship between them. Now what?
You need to know the song. Get the song in your head. Memorize the melody. Learn the chords on Piano, even if that is not your instrument. Learn the words to the tune if there are some. Play long passages over each chord on your instrument, to get the various sounds of it in your ears. Come up with phrases that work over subsets of the chord changes, like the ii-V-I sections etc. Play along with iReal Pro or some other automated rhythm section.
By the time you get on the stand to improvise, you should not be thinking about the song. You should be getting ready to tell a story. There are a couple mental techniques you can use to develop your solo. You can build up from a musical phrase, or you can mentally tell yourself a story and play the words that you hear.
When you build up from a musical phrase, you are going to take an idea, state it and then modify it through out the solo. You want to give the audience a hook to identify. It can start with a fragment of the melody line, or a phrase in your head. Something rhythmic. Something melodic. Repeat it, as close as you can, over the changes. Even if you play the exact same notes, it will have a different effect over different chords. More likely, you will want to adjust that phrase as the chords change. Add on to it. Drop notes from it.
Sonny Rollins’s solo on “Tenor Madness” is a great example of building up a fragment this.
One technique to use, but not over use, is to quote from a well known other song. A friend of mine opened a solo by playing the first phrase from “Sanford and Son.” Quoting a phrase like this is a shortcut to connecting with the audience. It can also be fun to throw a quote in to the middle of the solo, but make sure it makes sense in the context of the solo.
You can think words in your head, and play those words. Improvise a story in your head, about Meeting Miss Jones or Something that Happened ‘Round Midnight or who you met On the A Train. You may want to pretend to be a character when you do this. Humphrey Bogart as Sam Spade in the Maltese Falcon, turning up his collar and walking away into the San Francisco rain. You are doing a performance, and the more you are in to it, and get lost in it, the more your audience will link in to your world.
If you are still learning a song, you might want to use the lyrics to keep you in place, and play over them. You don’t replay the head, just use the words as a running commentary, and play “around” them as you solo.
If you are trying to play over “Donna Lee” you might find it easier to learn and track the lyrics to “Back home in Indiana” and keep those running through your head as you solo.
Build to a climax, conclude, and hand over the mike to the next player.