Dr. Tony Gutherie, a professor at Luther Rice Seminary, has written a fine book on expository preaching, Crossing the Homiletical Bridge.   One of the best passages in this book is his definition of expository preaching.  "Expository Preaching is: The oral proclamation of a properly interpreted passage of Scripture, in the power of the Holy Spirit, by a God-called messenger, to an assembled body, for the glory of God and the accomplishment of His purposes."  Do you preach expository messages?  It is my considered opinion that expository preaching is the best way to ensure each message you preach is Biblical.  After all Paul's command to young Timothy was to "preach the Word".