Hitler's SS wore black, with chrome trim no less. They looked fearsome. American police officers should wear blue, real blue, not a blue so dark it looks black, to show that they are civilian police officers, not SS thugs. They should wear police officer caps, with a brim, and the traditional eight sided cover, not the Air Force 50 mission crush, and not the Wehrmacht peaked cap, and not crash helmets.
Many, perhaps most, crimes are solved when someone gives the police a tip. If the public doesn't like the police they won't give 'em any tips. All professional police officers understand this and go to great lengths to establish good community relations.
Community relations can be difficult when the community has a high proportion of real criminals and wannabe criminals. I mean, the business of the police is to arrest criminals, and criminals don't like that. Best the police can do is contact the law abiding members of the community, clergy, store owners, business men, school teachers, boy scout leaders, citizens of good will, and establish some kind of rapport. Once established, use the rapport to communicate the police side of controversies to the community.
And, communities need to reduce the number of laws that they have the police enforce. For instance, the Garner death on Staten Island came about thru police (five officers no less) enforcing a law against selling loosies. Granted, the police were acting at the behest of neighborhood merchants who wanted Garner gone from in front of their establishments, but the loosey cigarette law gave a pretext for hassling an undersirable. Police should not get into enforcement and arrests unless real harm is being done. Unnecessary laws ought to be repealed before they cause trouble.