The first crime- I mean, not a crime, so much, but hey- she stopped was when she saw a pony crying because a pony who was corrupted had bullied the initial pony. Blue Raven investigated, and discovered that the bully didn't mean to be a bully- they were just corrupted. So, she brought the two ponies together and they talked. :3 That is when Blue Raven discovered her love for helping ponies. Not full of action, but it eased her into it.
Yup!
She had always loved martial arts as a filly, and taught herself. She put more effort into it after becoming a hero, though