I see this thread has calmed down a bit, regardless I will add my 3 cents (2 is being cheap)

I would reiterate what the guys have mentioned, but not knowing what your situation looks like, meaning layout of the yard/house, possibility of owning dogs (also limitations on breed/size/number) etc, I can only advise on what we have done.

On the farm, being a huge risk of armed attacks we have the following:
1) Big and small dogs (2 x boerboels and 4 pekingese halfbreeds), all sleeping inside with the small ones having a doggy door to get out;
2) A fence and motorized gate;
3) Motion sensors connected to a siren and alarm system which sends out calls to the neighbors;
4) A few spotlights around the yard to allow for sufficient light when peeping out the window when you hear something;
5) Enough spotlights to light up the darkside of the moon, aimed in such a way that they eliminate all dark spots (this was done over a period of a week's nights with all the adjustments etc), these spots are activated by beams set out around the premises. The beams show the area which is activated as well as activates all the spots.
6) Burglar bars around the house;
7) Safety gate in front of all the doors, you open the wooden door to the inside and the gate to the outside;
8) Various security gates throughout the house that get's locked at night and when we leave, basically a second & third barrier inside of the house.

Regards
H