I think humility is highly important in making a great preacher. I think truly great preachers exalt Christ, & not themselves. I think one of the most important parts of being a great preacher is realising how weak we are of our own selves. Paul said when I am weak then I am strong, because he was forced to rely on Gods grace. I think one of the most important aspects of being a great preacher,is praying alot & hearing from God !!! Paul the Apostle had something to say only because he was intimate with Christ. The most powerful preachers I've ever heard had an undieing love for Gods Word, & powerful prayer lives.The most powerful preachers I've heard were annointed of God, & had a burden for souls. Powerful preachers who impart truth are usually in love with Christ. If they are not in love with Jesus, then I would say they probaly are a hireling.Paul preached out of a passion for Christ. He said for me to live is Christ, & to die is gain.This is just some food for thought. I am sure there is a lot more that goes into the making of a great preacher.