Preach with Unction
"And when they had prayed, the place in which they were gathered together was shaken, and they were all filled with the Holy Spirit and continued to speak the word of God with boldness." The anointing of the Spirit is necessary for true boldness in preaching. Apart from the Spirit's empowerment, a preacher might muster some fervor, but he will lack authority, and might not even possess the courage to maintain God's truth before sinners. The right proclamation of the Word requires holy unction, which comes by the grace of God through prayer.