Remember this: The more you do it the easier it will become and you will be able to it more quickly and accurately. Just do it!Hi, all my playing has always been done by reading music sheets, what is the best way to progress to playing by ear, I struggle as soon as I move away from the written music, any suggestions please.
And of course that's what you need to know to improvise on the tune. I do think you can learn and memorize a melody without knowing the chords, etc, but without knowing the chords and song form it will be difficult to create your own melody.1 Learn the song form: AABA, ABAB, AAB, blues, 16 bar, etc
2 Learn to sing the melody by ear
3 Memorize the chords
If you can do these 3 simple things, you'll be able to play the melody by ear without too much trouble.
One thing for sure, at least in my own case, is once I really learn a tune without any sheet music in front of me, I can play it much better since I'm using my ears instead of my eyes. I also have the melody and sound of the chord progression internalized so I can play it with a lot more authority. I don't know if this is true for everyone, but I suspect it's pretty common.