Joy Lawson, the wife of Leroy Lawson (founding preacher of the church where I serve) made this helpful comment to her husband about his preaching:
"When you begin working on a sermon, you begin working on Monday morning. You work all through the week and you finish it up on Saturday. On Sunday morning you take off where you left off on Saturday, but we’re still back at Monday."
We all would do well to follow that advice and preach simply.