The work of the evangelist is to preach for conversion. This means for the souls that hear the Word to be called to turn from unbelief to belief in the Lord Jesus Christ.
The Lord Jesus should be the center of your message and your message should leave no doubt as to what you want these souls to do.
Salvation, reconciliation with God [II Corinthians 5:17-19], eternal life [John 17:3] and growing in the grace and knowledge of the Lord Jesus Christ [ II Peter 3:18] begins with repenting of not believing in Him to believing in Him.
Finally, when your hearers walk away what do you want them to remember? That they must repent and call upon the name of the Lord to be saved [Romans 10:9-13].