Two decades after his conversion, Paul is arrested for inciting a riot and uses the opportunity to give his testimony in front of his Jewish countrymen, and King Agrippa in Jerusalem. Paul called his captivity in Rome an “appointment” (Phil 1:17) and Jesus said that you will be dragged in front of men, for the purpose of preaching at them. (Matt 10:18) There is a time and a place for "Testimony Evangelism" and Acts 26 provides a good template for doing so. Acts 22 tells a similar story, but with a bad outcome. Certain portions of Acts 22 are added below:
Introduce Yourself v2-8 - Find common ground with your audience, tell the truth, if you were well on your way to being the highest Rabbi ever to live, don't downplay your position to say you'll never find true happiness without Jesus Christ. Saul had no such God-shaped hole in his heart.
Share Your Sins v9-12 - Give a good definition of your sins, always remembering that through the law comes the knowledge of sin (Romans 3:20) and why you need salvation, list the big ones first, then the smaller ones. Make sure to point them skyward! (Psalm 51:4)
Conviction v13-15 - Tell how you were introduced to the knowledge of your sins, if a light brighter than the noon-day sun shone on you (v13), or if the Word spoke to you (v14), or if your conscience convicted you (v14), or all three; the Holy Spirit loves to use this tool. (John 16:8-11)
Good News! 22v12-15 - Who and how you heard the Good News. In Paul’s case it was Ananias; who opened your eyes to the truth?
Grace 22v16 - Explain when you gained the knowledge that your sins were washed away. The truncated version in 26v16 shows the resurrection of Paul to walk in newness of life.
Fruit v17-20 - How has God used you since conversion?
Persecution v21-23 - You can do all things through Christ who strengthens you, if the world hates you, know that it hated Him first.
Defense v24-26 - Stand firm in your testimony. (John 18:37)
Call to Repentance v27-29 - Use your testimony to reach out to others that they may be made free of their spiritual bondage.
Notice specifically that Paul did not mention Hell in either of his testimonies. Paul believed fully in an eternal Hell (2 Thess 1:6-10), so the fact that he didn't mention it should be our lesson that Hell is not always necessary. Show your audience their offense against God and the reconciliation available only through Jesus Christ, then let the Holy Spirit do the rest.