I find that a typical response to Jehovah's Witnesses who are canvassing a neighborhood is to be brusque with them and then slam the door in their faces.
I have even had some of my high school students recount with pride such actions taken by their parents when Witnesses came knocking at their doors.
From the Witness's perspective, you are not debating the meaning of the biblical text so much as the religious authority behind any given interpretation.
Since he is conditioned to accept the Watchtower as God's "sole channel of communication" on earth, your ability to wield biblical Greek will likely count for naught.
Get them to tell their stories so that they are relating on a person-to-person level rather than regurgitating Watchtower beliefs.
Based on my experience, I would like to propose a list of five "no-no's" for a typical encounter with Jehovah's Witnesses.
You don't have to be a skilled apologist to practice these guidelines. This simple point could mean the difference between the loss of the souls of your Witnesses or their salvation.
The Witness will merely resort to the party line for any passage being discussed.
He is more than prepared to confront you on major doctrines, with special emphasis placed on Jesus' divinity and the Trinity.