The most effective way to deter an intrusion into your property is simply to show that it is being actively defended. A good example is the signs that are commonly placed around homes announcing a security system is installed or at businesses marking the position of cameras – the idea being that if the potential criminal knows that their intrusion has been prepared for, they will not attempt it.
A perimeter barrier is another effective element in a deterrence operation. While most fences provide only a minimum of effectiveness as a delay barrier and thus should be paired with other defensive environmental elements, as a perimeter barrier they are very effective at marking property lines and removing any doubt that a trespasser did not know they were in an unauthorized area.
When a security officer is responsible for defending a property, they will almost always have a patrol schedule implemented as part of the post orders (unless their job duties keep them tied to one area, such as a guard shack at the only accessible entrance). This is partly so the guard can observe the entire property, but arguably the more important result is that the guard makes himself and his active defense visible to anyone who would look to break in.
Exploring What Creates A Protected World