[orthoganol]

> be confident enough to start purging negative people

Except at 18 it's often your own raging insecurities that instantly label people as bad. More so, the main thing to tell my 18 year old self would be to just relax and open up around people who knee-jerk make you feel insecure - athletic, good looking people, really smart over-confident people, attractive women, etc. I put up all sorts of defenses when I was younger, and I paid for it, even now moving into my 30s. It's obvious now I could have easily befriended these people, or dated others, if I had just relaxed and kept my wits about me.