That brings us to the next essential in the preacher’s life—the reading of the Bible. This is obviously something that he does every day regularly.
My main advice here is: Read your Bible systematically.
The danger is to read at random, and that means that one tends to be reading only one’s favourite passages. In other words one fails to read the whole Bible.
I cannot emphasise too strongly the vital importance of reading the whole Bible. I would say that all preachers should read through the whole Bible in its entirety at least once every year.
Martyn Lloyd Jones, Preaching and Preachers