I kind of do it the old fashion way, "If you died this very moment, where would you go?"
If the response is "the grave," you can almost bet they are not familiar with life after death.
This leads to the conversation of, life after death, which then leads to Eternal life or Eternal death. Then most ask right away, how do I get Eternal life? And now it's all basic Gospel of Yeshua from that point.
And for those that just blow you off with something like, "there is No God, and we end up pushing daisies from the ground forever."
This is where I just tell them, "one day you will see that your point of view is incorrect," and end with "You will be in my prayers."
One person did ask, "what will you be praying for about me?" I responded with "that whatever it takes, God make yourself known to this person so they wake - up!!" That led to, "what does whatever it takes, mean?" I simply say, "it means, if you need to become crippled, find yourself in a near death situation, experience some horrific tragedy, whatever it requires for you to get a clue, do it and wake this person up."
Generally, the look upon their face says it all.