To learn how to solo, start with this simple step: block out a week and find a solo that you love. Make sure it’s not just full of virtuoso technique, but that you can truly imagine yourself playing it (if you just knew how). Make it is slow enough to comprehend the pitches and rhythms (for example, Miles Davis’ solo on “So What”).
Then, for one week, listen to the solo five times a day. After day one, start singing along, and sing along every day thereafter. After a week you should be able to sing with the soloist or on your own. Then, try to play the solo on your instrument.
This procedure will greatly develop your ear, help convince you that you are serious, and start you on your path to appreciating the jazz language. To amp up this exerise, try one solo a week for ten weeks.
Remember, if it’s not in your head, you won’t be able to play it, unless you know what it looks like on your instrument, which is a far cry from hearing it in your mind while you are playing it. Try it and see. You won’t be disappointed in the results.
Here’s Miles Davis and “So What”: