Leslie, I would bring up baptism. Perhaps you could say something like this:

"You are saved the moment that you turn from your sin and your own way to believe in Jesus as your Savior and God. Now, that is invisible; I cannot see the moment you believe. However, God commands everyone who believes to be baptized. [Perhaps some more explanation on baptism] I want you to let me know when you want to be baptized."

The greatest difficulty in personal evangelism is what to do "at the end." After explaining the gospel and making sure they understand it, you issue a call to belief. What is the positive response to that? Well, belief. But I think we tend to want some sort of "signal" that belief occurred. That's why in broadly evangelical circles you see things like scripted sinners prayers, spiritual birth certificates in the back of tracts, etc. But baptism is a divine command and accompanied the call to salvation. The Ethiopian eunuch understood this and suggested it himself. I doubt your friends are theologically savvy enough to figure that out on their own, but you could suggest it.

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Charlie Johnson
Heritage Bible Church (non-denom)
Greenville Presbyterian Theological Seminary, student