Select a song �then play the same song in many different keys. You will learn a great deal about chord progressions, which will help you play without music. If you hum or whistle the melody you can find the melody on the keyboard, But---- not so with chord progressions, you must learn and understand about chord progressions.
Years back when the song More came out I looked at the music and found the main part f the song had the Heart and soul chord progression. The release was a run down in E minor. I no longer needed the music.

No genius, just a knowledge of chord progressins.

John C.

PS, Heart and soul � Silhouettes � Blue moon � and many, many others use the same chord progression. (In part)
More � My funny Valentine --- Feelings � How deep is the ocean � all use a minor run-downs.

When improvising I look for key centers, that�s when the chords become different in a song. There�ll never be another you is in the key of Eb, the second chord Dm7 which puts me into the key of C major. When I am in the key of Eb I am thinking the Eb scale. When I see the chord Dm7 I am using mostly white keys, the key of C major.