The BEST lesson I ever got was from a family member's boyfriend, who was a music major when I met him in the 70s. He told me to memorize the chords, not the melody. If you know the chords, and you train your ear to listen ... you can go much further. The melody is easier to "hear" once you know the chords. Ask any horn player, and they will tell you the same.

Second best piece of advice I got was to sit in with as many players as possible ... preferably better musicians than myself. Learn from them.
Served me well, all these years.