This information is taken from True Identity: The Bible for Women (published 2005 by Zondervan, copyright 2005 by The Zondervan Corporation).

“Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have” (1 Peter 3:15). How many opportunities have you missed because you were unprepared or unwilling to share your faith? For many people, the answer is “too many.” The most powerful evangelistic tool you have is within your grasp. It’s not a seminary degree—it’s your personal testimony. Why? Because you are the expert on what happened in your life. People may debate the reliability of the Bible, but they cannot refute your personal experience. Your testimony can be a spiritual tie-in at any point in a conversation. But you must be prepared. You should be able to tell your testimony in a short version (less than one minute) and in a longer version (three minutes max). There are three parts to a personal testimony:

• Life before Christ. Choose a descriptive word for your life before Christ. If you were a child when you became a Christian, think how your life might have turned out without Christ. Your word might be, "empty," "boring," or "purposeless."
• How you became a Christian. Where were you? (At church, at camp, at home?) How did you become a Christian?
• Life after you met Christ. Choose another descriptive word for your life as a Christian. You might say something like, "meaningful," "fulfilled" or "exciting." Describe some tangible benefit that God brings to your life today.

The most important and powerful part of your testimony is not what your life was like before Christ—it is the difference he makes in your life now. This should be the longest part of your testimony, and it is what will appeal to people. Because God is always at work in your life, keep your testimony fresh and updated. Look for opportunities to tie your testimony into everyday conversations. With practice, you’ll become more confident in sharing your faith and even more aware of the many people you encounter who will be changed by your story.