Thought this might be good place to share a little trick I use.
First though, I've always divided up "defense" into several categories.
Early Warning
Target Hardening
Subtrafusion
Passive Protection
Action
Let me share, my early warning, which has worked quite well.
My Bichon, Whiteout (whom I now call her Michael the Wonder Dog) barks only when important things happen, like a leaf falling in the next county. But, like most dogs, she produces too many false alarms and is easy to ignore. (She has, to her credit, saved the house from burning down by alerting us of a fire....another story for another post.) However, I devised a method for detecting most attempts to approach my home. And for detecting attempt to TP my front yard.
I live in a typical Atlanta subdivision of 3/4 acre lots, but my house is unusual in that the driveway is 125' long and most of the front yard is un-cleared. So it's natural to come down the driveway regardless of your intent. Behind the mailbox is a large bush (5'h x 4' diameter), and right behind that is a small flagpole. I ran electrical wires to the flagpole and mounted two motion detectors WITHOUT their lights about 3' high on the flagpole. One is pointed to the driveway and one to the cleared part of the front yard. With proper adjustment they do not detect cars in the cul-d-sac or in the neighbors driveway. NOW, and here's the twist, I ran the wires, normally used to turn on lights, back to the house and hooked them to a relay, which in turn activates the house doorbell. (I put an extra bell in my bedroom to insure I couldn't ignore it.)
So try to cross my yard or walk down my driveway and my doorbell alerts me you to your presence. Unless you're running, I have about a minute to check out the window and take action. Yes the occasional rabbit or possum wakes me up, but it is a small price to pay. It can false a lot during the day with squirrels, so I put a switch on it in the kitchen to deactivate it.
No one comes to my door at night without me knowing about it first. And if I'm expecting a delivery, then I turn it on during the day, while I'm working in another part of the house. Works good on Halloween too, though MTWD seems to have that duty nailed.
I used the existing doorbell circuit because it was there, but there's no reason why you can't have a separate alarm, other than the wiring involved.
Alf