Hello Cordelia,
I cannot emphasize this strongly enough: They lie about almost everything.
They practice deliberate deception when quoting outside sources. They practice deliberate deception when retelling their own history. They engage in basic logical fallacies in issue after issue of the Watchtower and Awake! magazines. They demonstrate that they care more about advancing their own doctrine than the actual facts in their literature. There is precious little of anything approaching truth in the WTS.
If you're unsure, take the time to research things carefully. If there is one sure thing in this world, it is that the Witnesses are not what they claim.
If I were you, I would start by reading Ray Franz' Crisis of Conscience. This will give you a very good place to start.
SNG