How can I improve my original music compositions?

more of a personal preference thing, but i was hoping to hear you at some point make the e flat (the minor 7) in the intro part move down a half step to d, and accompany it with a B flat major chord (IV). also, i think that the part that comes after that would be much more interesting if you utilized secondary dominants. there were some parts that sounded like they were leading up to it, but didn't.