Here are a few thoughts:
A Sermon is God’s Word expounded to a local congregation.
Christ is the Great Subject of the Scriptures.
Context is King: “A Text without a Context is a Pretext.”
Expository sermons usually are grounded in studies of entire books of the Bible so the message God intends is paramount. Topical sermons are permissible but must also be expository and thus grounded in a serious exegesis of a given passage.
Once I preached a sermon on just one word: ethelothriskeia, (will-worship).
The preaching of God’s Word is God’s Word.
No matter how long a sermon is, it should “seem” like 20 minutes!
Passion is always welcome.