What can be done to prevent tragic shootings, outside the scope of gun control?

Disclaimer: This isn’t a debate about guns, whatsoever. I want to try and stay away from mentions of guns.
I’m asking for things, outside of guns, that can be done to prevent shootings at schools, specifically.
They caught the shooter of Florida, which apparently is very rare because they usually kill themselves. I’m hoping they will interview him, figure out his state of mind/more about why he did it, and then put steps/programs in place to stop it.

This question is asking more about what you think should be done to prevent school shootings inside a school meaning should the school be educating students on getting help if they feel like that (homicidal), doing more about bullying, etc. Instead of saying “here’s what to do if a shooter is in the school”

My school has a cop that walks around all day. Has his own office and parking spot. I think that might be a good start for most schools but then the issue is paying the cop.

I’m trying to think of an easy, simplistic way to ask this question, but I’m having a hard time so hopefully I’m not being too confusing