First thing: Work out the structure (particularly important for gospels because it can be hard to tell!)
To preach on a bit, you have to have some idea of the purpose of the gospel, where the gospel writer is going with this.
Encouraging us to work out our own idea first before bouncing off other people's structures.
Two levels of structure: the structure of the book, and then the breakup you do for your preaching series.
"The question that I keep coming back to in how to break up passages into preaching portions is: will this break-up help people learn to read this book for themselves?"