There's an interview on the web with Carol Kaye (most recorded musician, guitar and bass): the first half is pretty much a master class. Recognize that modern music is harmonic so learn chords not notes and learn chord cycles - endless music is based on that. With little difficulty you can then play many recognizable tunes by ear and many more that sound familiar but are purely made up. Start with a basic 3 chord gospel tune and then expand it to 4, 5, 6, 7 chord variations until you wander into a different tune. Of course, Pachelbel's Cannon has been plagiarised in dozens of tunes so it's a no-brainer as general purpose fodder. Of course there's always plain old 1-4-5 12 bar noodling; a buddies dad showed me a basic boogie version: right hand C6(1st inversion), F7(4th inversion), C6(1st), G7(3rd). etc. when I was 12 - something you can endlessly build on - solid/broken/1-4 rocking etc. (I'm giving away my age but 80% of the album 'Introducing the Rolling Stones' explores this: we comp'd it all).Most friends and family know that I have played piano, now keyboard for a very, very long time. I own a Yamaha DGX660 and certainly get my monies worth out of it. I was classically trained from the age of 5 and in recent years have made great strides in playing by ear, improvisation and even dabbling in jazz and blues.
For fun, I have decided to challenge myself to learn and memorize three songs. Songs that people would enjoy when I hear
"I heard you play piano, play something for us!"
What should those three songs be?