Know what the old masters did. Know how they composed their pictures, but do not fall into the conventions they established. These conventions were right for them, and they are wonderful. They made their language. You make yours. All the past can help you.
In the past, I'd sort of know before Ozzy sang something, what he was going to sing. I'd know what sort of way a melody was going to go 'cause of the way he'd approach it.