Here are some questions that I use from time to time when I encounter someone who is a professing Christian:
1. Do you share your faith?
2. Do you go out of your way to share your faith with strangers?
3. What do you say to people when you witness?
4. Do you ever mention judgment day?
5. Do you ever mention Hell?
6. Why should someone become a Christian? (What do they get out of it)?
7. Who in your life isn't saved or born again? Where will he/she go if he/she dies without Christ? 8. If a blind man were walking toward a 1000 ft cliff, what would you do? Let Him know about a good church? Warn him about the cliff?
9. If a non-Christian is unknowingly headed toward eternal Hell, What should you do? Invite him to church? Warn him about Hell?
10. When was the last time you read your Bible?
11. How often do you read your Bible?
12. How does someone to become a Christian?
Feel free to copy and paste this list and carry it with you. It might help jog your memory right before you go out to witness. These questions will come in handy especially if you are living in the bible belt like me. :-)