Welcome back! There are many ways to build your repertoire. Traditionally, jazz was shared aurally. Young musicians would learn new tunes from mentors, other musicians and recordings. However, you may not have a large group of jazz musician friends, or you don't have the skillset needed to learn harmony aurally. Since you're a classical vocalist, I'm assuming you can read music, so let's take advantage of that skill. As you progress, your aural skills will improve dramatically.
Most jazz musicians have a large collection of what we call “Real” books or “Fake” books. Even though they are opposite words, they mean the exact same thing when it comes to a collection of songs in a book. These books generally have just the melody, the lyrics and the chord progression on a single page. You're going to need at least one book of tunes to get started, so let's look at what makes a good real book.
A good real book is copyright legal. There are a number of books that circulated through the jazz community for many years that were hand-written melodies and chords taken off of recordings. These books had a number of problems. They were notoriously inaccurate, and they were not copyright legal, which meant that the composers and copyright holders never received their fair share. Years later, publishers finally realized that there was a huge demand for accurate, clearly notated jazz standards so they started publishing legal collections of the most popular jazz standards.
When I talk about “jazz standards,” I'm referring to a canon of certain compositions. In classical vocal literature, the “canon” includes pieces such as the Italian Songs and Arias, Bach Cantatas, and French art songs. The jazz canon includes standards like “Satin Doll” by Duke Ellington or “Night and Day” by Cole Porter.
You'll want to have a variety of different types of songs in your repertoire, with a combination of medium swing tunes, latin tunes, ballads, up-tempo “burners” and contemporary tunes. Resist the urge to build your repertoire around ballads. Consider having songs from two of the other categories to every ballad in your book.
Focus on songs that everybody knows and loves, but also consider having a few lesser-known tunes to add interest to your sets. This can also include a couple of originals if you compose.
Homework – Go to my Resources page and look through my list of 100 Jazz Standards for Singers. Choose the first few songs you would like to begin with. Choose one medium swing, (8th notes are not equal, and the tempo ranges from 100 to 200 BPM) one up-tempo swing, (tempos above 200 BPM) one ballad, (straight 8th notes, tempo range from 60 to 90 BPM) and one Latin tune (these generally come from Afro-Cuban or Brazilian jazz and have straight 8th notes.)
Stay tuned for blog #3 - Figuring out your key. See you soon!