Sometimes after finishing a witness encounter, especially with an old friend or a family member, the conversation tends to get away from spiritual things. So when you part ways they are still reminiscing or smiling about the last half of the conversation. This is not good because you want them to continue to think about eternal things especially those who did not receive Christ as Saviour.
There are two options to prevent this from occuring. One is to end the converstation once you have finished witnessing and the conversation goes astray. Or two, use "the last thing said" technique. The theory is that the last thing said is the first thing remembered.
What I like to do is this, once the conversation has gone astray and we are wrapping it up I love to look them in the eye and say,
I then remind them to read and review the tract(s) I had given them.
"Before I leave you I want to remind you this. By your own admission if you were to be judged by God using His 10 commandments you would be guilty. So if while driving home you were to get in an accident and die you would go straight to hell. I want you to think about what we talked about as your driving and I will be praying that you get right with God before its to late!"
This has been a great technique. I think it reminds them the seriousness of the situation and puts their mind back on the things of God. You should see some of the facial expressions from the lost and other evangelists when I say this. The lost sometimes looks terrified as does the evangelist.