If you are continuously reading and studying the Word of God. You will be prepared when the opportunity arises.
“I solemnly charge you in the presence of God and of Christ Jesus, who is to judge the living and the dead, and by His appearing and His kingdom: preach the word; be ready in season and out of season; reprove, rebuke, exhort, with great patience and instruction.”
2 Timothy 4:1-2 NASB