I would advise you to keep it simple, and non-strident sounding.. I and other normal people find actual Watchtower quotes quite revealing. I like to let their own literature prove exactly how they feel about these issues.
Also include websites such as these for more detailed information
http://www.ajwrb.org/ for blood info
http://www.freeminds.org/ for general info
Too bad dirtclod is gone. That one was great to show the TV shows about Witnesses.
As someone who has never been a witness, what I find most horrible includes:
1. people dying from lack of blood from acute bleeding and complications of cancer chemotherapy and the medical inaccuracies taught by the Watchtower
2. the shunning done by family and friends to anyone who disagrees with the religion or leaves it
3. the reasons they DF people, including smoking and even questioning any Watchtower policy
4. that they consider the rest of the world "bad association" and that they believe we will all die at Armageddon.
5.that JWs are not to date, or get involved with Non witnesses, and the consequences that can happen if they do get involved.
6. that the woman must be in subjugation to her husband and obey him even if she knows he is making a wrong decision.
7. rape is not rape unless the woman screams (is that still current policy?)
8. the two witness rule and its implications on child abuse and marital abuse
9. elders, who are not trained in psychology or counselling, having an intrusive and controlling place in Witness's lives including their marriage
10. that Witnesses are advised to break legal and medical confidentiality to speak to the elders about something they might see at work.
I know there is lots more, but this is just the ones off the top of my head.
Please check your inbox later. Good luck. I think it is a great idea, as long as you are calm and factual about it..