Staying out of Prison

I'm new to the black hat scene and I was wondering if there are any practices people should stay away from if they don't want to end up getting in trouble with the law.

Is there anything lots of people do that they probably shouldn't because they could end up getting in serious trouble?

Blackhat doesn't mean illegal. Stay away from doing illegal things and you'll stay out of prison

A big one would be mass emailing. Stay away from mass emailing people who did not opt-in to receive your emails unless you really know what your doing

I know black hat doesnt mean illegal, but there's a big difference between getting your IP banned from Facebook and the cops showing up from your door.

Sometimes it's hard to tell what could get you in deep water. I'm looking for things that people need to look out.