To start: Change school hours completely. Shifts of virtual schooling then shifts of on campus schooling. Not to ever have a school completely vacant for a week, but to lower the numbers coming in/out daily. Just totally switch up the typical schedule if at all possible. Being a predictable sitting duck is never a good idea in any scenario. I think the patterns should change often, maybe even monthly.
I know a majority of schools have these, but sadly, metal detectors should be in place everywhere until we get it under control.
more/quality parking lot security.
All doors must lock once classes are in session. No exceptions (that includes side doors and back entrances)
Maybe this is already a thing, but implement self-defense classes as CE's (Personally think it should be required) but we have to start switching our mindsets to, how do I not become a sitting duck? there's typically 1-2 shooters vs. hundreds of defenseless victims. Theres power in numbers and we need to start using that to our advantage.
As far as personal responsibilities: from one human to the other, do your best to put an end to bullying. Be there for someone. Stick up for someone. Reach out.