I don't have it set to high security, but then thankfully I also have an extremely common name, like Jane Smith. So if anyone's wanting to find me specifically, they'll have to hunt through all the other same names as mine.
I'm not particularly active either. I use it more to keep up with a small handful of friends. And I only have people on my friends list who I know (either good online friends or people irl).
Main thing is never post on FB something you wouldn't want your employer (current or future) to know about you.