Choose the introduction's practical job
An introduction should help the listener and performer understand the tempo, tonal area, and character of the song. It does not need a complicated new harmonic idea. Start with a short portion of the main progression, such as the final two chords leading into the verse. Decide exactly how many measures you will play. A singer needs to know when the opening phrase begins, so avoid an uncounted flourish that changes length every time you sit down at the keyboard.
Use a small recognizable gesture
Play the chosen chords with a simple texture that resembles the accompaniment you will use under the voice. You can add a short original melodic contour drawn from chord tones or a permitted motif from the song you are arranging. Keep it easy enough to perform while giving a visible or audible entrance cue. End in a register that lets your hands move naturally into the verse. If the last introduction chord differs from the first verse chord, practice the connection rather than treating the two sections as separate pieces.
Rehearse the entrance with the voice
Count the introduction aloud, then sing or invite the vocalist to enter at the planned point. Include any pickup syllable in the count so the first word is not mistaken for the downbeat. Use the verified AudioChords sequence as a harmonic reference, but remember that your live introduction may be an intentional adaptation of the recording. Repeat the opening several times with the same length and tempo. A useful introduction makes the first phrase feel inevitable. Add expressive detail only after the basic entrance remains clear to someone who is not watching your hands or reading your private notes.