Is there an easy way (for beginners) to add a solo section to a piece of music, like a lead sheet from the Real Book?
I am thinking in terms of a chord progression. Would I repeat a progression from the main section or from a chorus, and improvise over that?
Listen to a recording of the piece and see what sections are used as a solo section. It differs from piece to piece, and my guess is that there is some flexibility with it, as long as the chord transitions from the end of the head of the piece back to the beginning of one of the sections is smooth. Say a piece has A, B, and C sections. Some will use all three as a solo. Some will use A as a bridge between solos and solo over B and C. Some will finish the head and return to just B or C for solos. It really depends on the piece and how close you want to stay to the original way it was done.
As Heather says, you can use any section you like to solo over. The verse is probably one of the best, as if it's a vocal piece, the singer can pick up straight after the verse you solo over, and into another chorus.
But, each piece will have its own geography, and will lend itself better to one particular part. For an inexperienced player, the part with fewest changes, or uncomplicated chords may be the best part.
Depends on what you are trying to accomplish. The question first seemed strange to me. In Jazz it is typical to play the head, maybe twice, and the go - take off. And yes, you typically just solo of the changes of the song playing through several times (the etiquette I learned was multiples of 2 cycles through the tune then hand it off). So, if you are asking about soloing over changes you just lay your licks over the changes.
Now, the rhythm section can get creative in their interpretation of the changes with substitutions and cycle extensions but unless they're being mean they will stick to the structure and be "supportive". Some artists set up different changes for a solo section. A perfect example is West Coast Blues by Wes Montgomery. The solo section has different chords (more intricate) but it still follows the 12 bar blues pattern, it does not go off into left field.
Lastly, if you are thinking of throwing in some avant garde middle section to Autumn Leaves or How High the Moon I don't have any advice. That is beyond me. If you are interested in understanding substitutes and cycle extensions you might try the following book:
How to Create Jazz Chord Progressions by Chuck Marohnic
My guitar teacher took me through that back in the 80s.
When playing jazz standards from the Real Book, the improvisation always occurs over parts or all of the existing form/chord progression. The way these songs generally progress is:
If a song is faster ("up tempo"), solos typically occur over the entire form/over all of the chord changes. This is especially true for songs that are shorter in length (12 bars, 16 bars, etc.). If you're playing an up-tempo 12-bar blues, soloists will often improvise over many iterations of the form.
Ballads are played at slower tempos and typically have longer forms (e.g., AABA). For these songs, it's common for a single soloist to blow/improvise over just half of the song (AA). And after solos are finished, it's also common to start the final iteration of the melody at the bridge/B section, e.g., so that the final performance of the melody is simply BA instead of AABA.
