Have you ever had to address an audience at a speech-giving event, a debate, or during a stage performance? Have you been asked to stand before a panel at an interview or an audition? We tend to feel nervous, anxious, and even scared when we have to face people, especially if they are unfamiliar to us. As believers, part of our assignment is to preach the gospel, and one of the most effective ways to convey the good news is through the use of words and wisdom. 
Effective speakers are charismatic and eloquent, have well-researched information about the topic that boosts their self-confidence, and can elicit a response from their audiences. While, as believers, we can take a cue from these abilities for excellent delivery, we should rely on the Holy Spirit to effectively relay the message of salvation. Apostle Paul tells us that it would require the working of the Spirit and His power for men to believe in salvation and also be grounded in the faith. Eloquent words or the intelligence of human wisdom cannot make men see the light of the gospel. 
You can depend on the Holy Spirit to give you the right words to speak and the wisdom to convey the message of the Cross to unbelievers, whether you are preaching or witnessing.

Dear Heavenly Father, thank You for the privilege to be a witness to the gospel of salvation. I bless You for making me a vessel through which many can be reconciled to You. Lord Jesus, I ask for power to be an effective witness for You. I pray that Your Holy Spirit will increase within me. I ask that He give me the right words to say anything I am opportune to preach the gospel. As I submit myself to being taught by the Holy Spirit, I pray that my words will be full of grace and seasoned with salt. They will minister the grace of God and edify whoever listens. 
In Jesus's name I pray. Amen.