Eugene Lowry gave this advice to young preachers:

I try to teach my students how to trick themselves into hearing. You have to be out of control. When you're in the driver's seat, it doesn't work. It doesn't matter where I open this thing up, I already have my theology. I just superimpose it. I don't tell the folks I do; I just do it so automatically I don't even notice. So you have to trick yourself to get out of control.

One of the things I tell my students at Saint Paul is sometimes to take a text that you're hoping to use in a sermon, underline all the important parts, and then look at what you did not underline. That's where God may speak. The Spirit may get real active at the point of confusion or at what we don't notice.

If it's a narrative with several characters, find out with whom you're identifying. Then put yourself in somebody else's shoes, and see if the Lord might speak.

Don't open a text or start first working on your notes--"What's the theme? What are the points I can make?" No. Don't start looking for points. Start looking for questions. Look for trouble. In the confusion of trouble is where the Lord may speak a new word. If we don't hear that word, how will anybody else hear it through us?