What you need to know about the JW/Watchtower society movement:
What are our responsibilities?
Difficulties: They’ve been brainwashed, they have everything to lose. They have been trained to argue in a certain way, they follow a script and are ready for certain responses you might give. They are unwilling to consider any other way, and unwilling to investigate anything else.
What can you do practically? Pray. Know Theology. Engage with them. Share the Gospel with them (don't get locked in never ending arguments).Encourage them to read scripture alone, without the Watchtowers influence.Research their Bible, look for verses that teach against what they believe, they do exist in their own Bibles (E.G. John 1:3, Isaiah 9:6, Titus 3:5, Ephesians 2:8-9).