Review and train.
How to deal with people full stop
How to deal with protests, rather than reach for the pepper spray, water cannon, tear gas or a even a gun.
How to deal with sexual assault and rape.
They have become a paramilitary organization rather than a police force, they need to remember that they are public servants and not mindless enforcers. They are there to protect and serve the public and not to menace with ever more sophisticated tools of war.
Personally I am fed up of reading about police brutality, victim blaming, and downright murder. They need better training and effective discipline, they are part of the community and not its controller.
I am fed up of the blatant bullying, racism, sexism and bigotry shown. Those police officers incapable of changing need to be removed from any contact with the public and preferably the service entirely; since they pollute the entire culture.
No Police service will ever be perfect, but the US system is so far from perfect as to have become an embarrassment. This is not new and it is long past time they changed their attitudes to society and if they cannot, they should be fired. Those that protect other officers should also be assigned other tasks, as they are part of the problem. I do not believe this is just one bad apple but a whole culture, them v us.
They are not the military, local militia or a paramilitary organization they are meant to be a civil police force. In fact they should be more rigorously trained and reviewed than any of our public servants and rewarded accordingly.