How do I reduce the amount of trial and error when making music?

I see those people, they just come up with melodies and chords on the fly. How do they do it without a bunch of trial and error?

Submitted January 13, 2021 at 10:11AM by AdministrativeBat486 https://www.reddit.com/r/Learnmusic/comments/kwg5nl/how_do_i_reduce_the_amount_of_trial_and_error/?utm_source=ifttt

Javier Rodriguez