I always tried to my best as a JW, to observe what the Watchtower and bible told us "not to do". Then I became inactive and lowered my guard, and didn't care as much. I think that my first JW sin, was playing lotto, then talking to disfellowshipped ones in my congregation, then posting on apostate forums, and then giving blood. Once you get to that point, you don't mind breaking more rules, unless it goes against your beliefs or conscience.
Which JW commandements did you break first?