There's never a guarantee in policing that a tactic will always work, but if the goal is to let people protest, not have people hurt, and end things peacefully, two cities serve as useful case studies.
In Hong Kong, protesters blocked major roadways for months (OMG, traffic was blocked!). Rather than cracking down and perhaps igniting a major revolt, the government waited it out. Police torn down the last camps a few weeks ago. In the end: "The Hong Kong government gave no substantial concessions, and the protest movement increasingly succumbed to exhaustion and internal fractures." This is actually somewhat similar to how the NYPD dealt with Occupy in 2011.
Had the law-and-order police come in and busted heads, who knows? We might have democracy in Hong Kong (and angry people in America). But my point isn't whether the protests are for a good cause or not, my point is there's a right way to handle protests if you don't want people to get hurt (or hand political capital over to the protesters).
Meanwhile in Nashville, Tennessee, the chief turned over a highway to Ferguson protesters and served hot chocolate. Of course a lot of people got pissed off at such treatment when he could have used tear gas and arrests. (And the freeway! What about the free flow of vehicle traffic?!)
In the end nobody got hurt and everybody went home. Chief Anderson wrote a nice letter in response to one complainer. Worth reading. Good on 'im! Chief Anderson seems to understand that protesters are not an existential threat to American values as much as heavy handed policing of protesters.