This is a great question and very practical in this economic climate. If communities police their neighborhood a little more, then not only will this create a safer environment, but also make save some tax dollars. In light of this, I can think of three things that people can do to police their communities.
First, the most obvious thing to do is to have communities watches. If there are signs up that the community is watching and the community actually does it, then this can be a good deterence. Many petty crimes take place, because no one is watching.
Second, communities can patrol the street after and before school to make sure that our children are well. My son's school makes all parents volunteer two hours a year. This is simple and effective.
Third, education about the law and the consequences of breaking it can be effective in creating law abiding citizens.