This is an essential tool for dealing with problems. Many times, for example, officers receive information from concerned citizens about possible drug houses in their areas. The typical reply from officers is a courteous expression of appreciation, a promise to "keep an eye" on the problem and, a few days later, file 13.
Ultimately this leaves the officers feeling ineffective, the citizens feeling like the officers don't care, and the problem still chugging along smoothly.
However, if these officers would simply exercise a little initiative by knocking on a door, engaging occupants of the problem location in conversation while looking around for any plain-view evidence, and then possible asking for consent to search, great things might happen.
The officers would feel empowered to deal with these types of problems. The citizens would feel the officers responded to their cries for help, and the problem would either be solved by a trip to the fray bar hotel or, at least, offenders would know the suspicious activity is recognized as a problem and feel some pressure. Either way, all the good guys win.
3. Hide and Watch: Using this technique, an officer parks or stands a discreet distance from a high crime area and, with the aid of binoculars, watches the activities in the area. Often, it will only take a few minutes of observing a person's behavior to develop reasonable suspicion.