I once lived in a grotty flat, in a high crime area.
If I was every going to be away for a day or two, I had lamps in the living room, bed room and bathroom, all on timer plugs. All set to go on and off at set times though the evening, and up to about midnight. Depending on the time of year, I'd set them to come on for a little while in the morning.
In another area I lived which was nicer, but still highish in crime, someone tried to break into our patio doors.
They were simple wooden frame ones, with a single deadbolt. Enough force could burst them open outwards.
I fitted two deadbolt catches, one per door, that slotted into the top of the frame.
The scumbags tried once more, but had no luck.
Same house, different occasion. Local douchbags were fence hopping and breaking into peoples sheds. The first I heard of this crimewave was one night. I was asleep but woke up to crashing and swearing in the garden.
As this happened only shortly after the patio door event, I assumed the worst.
So I snuck out the front door, round the side of the house and charged into the back garden, carrying something sharp and pointy I grabbed on the way.
I found 2 guys untangeling themselves from chicken wire. Twits had leapt the fence, and landed in the chicken run.
Shouting loudly, I ran at them (I know I know, stoopid) and they swiftly hopped the next fence and ran. I suppose me, with a big sharp pointy, and only a pair of underpants on was to much for them.
After that, I strategically placed 'clutter' around the edges of the garden. Next fence hopper to try would be risking a busted leg.
"There are none so blind as those who will not see. The most deluded people are those who choose to ignore what they already know."
Now if only they could put all that effort into, say, hammer throwing, we'd have some more olympic gold medals!
