Yes. Start giving the officers and the organizations that represent the officers (departments, unions) good reasons to kick out people who are a high risk of shooting people unreasonably.
Mandatory individual liability insurance would go a long ways. Holding police to the same standard as the rest of us would also go a long ways. Pretty much anything is better than nothing.
Cops shoot people dead in situations where normal armed citizens wouldn't even think about pulling a gun. Seriously, I can't even begin to convey how massive the double standard is here. Stuff that's justifiable when the cops do it would be an instant manslaughter if not murder charge for a regular person.
Unnecessary police killings are one of those areas where pretty much everyone pro-gun and anti-gun agrees that guns aren't the problem, it's hothead officers who don't de-escalate and pull the trigger at the drop of the hat that are the problem.