One thing you could do is expose how Jehovah's Witnesses, just like almost every other Christian denomination, fail to obey Jesus. According to the Watchtower, after the Apostles all died, the Christian Congregation became apostate (i.e. the Roman Catholic Church was born) and it wasn't until Rutherford in 1919 that there was true, pure worship on Earth. Take a look at the Christian Congregation back in the first and second centuries.
Acts shows us that Christians sold their land and belongings. The donated all their wealth to the congregation. All of it. They used these funds to take care of one another in a commune way of life. The whole "Ministerial Servant" arrangement was made because gentile Christians complained that their people were being provided for like the Jewish Christians.
They met in private homes and preached the Gospel. New converts were baptized on the same day they accepted the Gospel. Not one Apostle ever wrote a book on policy and procedure for Christian congregation nor was any book required to be studied by a convert prior to baptism.
So why don't Jehovah's Witnesses practice the true Christian life? Did Rutherford or any of his successors at the Watchtower have some sort of divine revelation that the Apostles didn't? You can't say that it is impossible to live this way in the modern world when these folks are doing it in our own backyard -