The problem with folks talking to the JWs is this: the mythology theology of the WT is so abstact and non-traditional that individuals do not know "where" the JW is in the conversation.
You do.
You "know" the cult conditioned language and the underflow of thought and emotion that are contained in the "coded" words and phrases of the WT.
And, from the comments on this board, many were looking for something better while in the WT.
So,
avoid the topics in which the JWs are well trained: trinity, state of the dead, and the kingdom.
Focus on the soft underbelly of the WT: central theme of the good news and the fact that one must falsify information as a pledge of loyalty.
Share a cup of coffee or a glass of ice tea. Show loving concern. An invitation to return. Build a personal relationship with the JW. Plant seeds that can be watered in places like this.
A few thoughts,
V