Here are some helpful posts on preaching:

The Greatest Preachers – Wayne Gruden (via Jared Wilson)
According to Grudem’s definition, we can all be great preachers! Indeed we must be.

Preaching Texts You Do Not Understand – Carl Trueman (via Reformation 21)
We’ve all been there. Here are some helpful thoughts.

Pastors, What You Preach Is Already Decided – Charles Spurgeon (via Desiring God)
We can’t make it up out of our own heads.

The Most Transformational Word – Paul Tripp (via Gospel Coalition)
We must preach grace to ourselves.

Preaching is theology coming through a man who is on fire.
Martyn Lloyd-Jones