I started by reading about Evolution. I cross-checked the quotations and statements made in the Watchtower books, such as Creation (1985) and Creator (1998), and found out that they were full of quote-mining and various other fallacies. A moment of revelation was when I cross-checked a certain Hitching (not Hitchens) who WTS presented as a prominent ''evolutionist'' who discredited evolution (!!), and found out that he actually was a charlatan with spiritist practices! That undermined my faith in the sincerity of Watchtower authors.
I then viewed the movie "To Verdener" (Danish), which is about a malfunctioning JW family. It presented a familiar scenery, though seen from a different viewpoint, more realistic, more cynical.
Then came this forum :)