How should police respond to protests?

I think we can all agree that how Ferguson was handled was wrong. [Link]

We then have an incident that represents all of these problems in a very concentrated form — an unarmed black man was killed by a (reportedly) white police officer who had stopped him as he was walking home. The police have since refused to release the officer’s name. They’ve said they have no intention of releasing the autopsy performed on Michael Brown. Police Chief Thomas Jackson refused to even say how many shots were fired at Brown. (He claimed he didn’t know, though that would be pretty easy to figure out.) Though the police department has body cameras, it hasn’t required its officers to actually wear them. All of this only adds to perception of a Ferguson Police Department that is detached, unaccountable, opaque, and unconcerned with how it is perceived by the community it serves. (Gassing, arresting, and threatening journalistsdoesn’t help with the perception that they feel they’re above transparency.) The police then showed up at a peaceful protest with military vehicles and weapons. If a town’s citizens are reminded over and over again that the law has no respect for them, we shouldn’t be surprised if they begin to lose respect for the law. This isn’t an excuse for the looting and rioting. But it does contextualize what we’ve seen.

This raises a question I’ve seen on Twitter and Facebook from a number of people — how should police respond to protest? And how should they respond when protests turn violent?