When it comes to communication-writing or speaking, and perhaps especially preaching-start with what you know and only what you know. Don't guess when you're handling the Word of God.
Give people more to think about besides, "I said so; the Bible says so; and that's final." Help them know why Christians believe what they believe about God, Jesus and the gospel.
When was the most recent time you prepared a sermon? Were you prepared to prepare? What steps did you take to get you ready to deliver God's message to God's people?