2" by 4" under the doorknob?
Radio with Fox News always on in a back room?
Dining room light is always on
A poodle that barks at everything?
Hockey stick in sliding doors?
Years ago when I lived alone, someone told me to put a big (preferably scuffed up and a little dirty) dog bowl of water on the back porch, along with a couple of large, beat up dog chews. I also don’t oil exterior hinges. I like to hear my doors.
Edit: Now I have four big, imposing dogs, so I don’t need to pretend. Def low tech, but not cheap, either.
Transform your house into an impenetrable black box from the outside. The less outsiders know, the less enticing it will be.
Since I live in a hot climate, I’ve installed UV window film and blackout curtains on all my windows, making it impossible for anyone to see inside. This way, someone observing won’t be able to discern whether my home has valuables or if the residents are present and capable of defending themselves. To them, it could look like six strong guys are inside watching a football game and getting frustrated with the score.
Ensure that the vehicles in your driveway reveal nothing about you. Remove any stickers that might give away details about your family (“My honor student goes to XYZ Elementary!”, stick figure families, pet stickers indicating you have cats but no dogs, etc.) or possessions (Apple logos, firearm stickers, “Member of [local bank]”, etc.).
Exterior lights are also a good idea.
All these measures contribute to the overall effect. When I step into my driveway at night and look down the street, I notice that very few of my neighbors have their outdoor lights on, and their curtains are open, allowing me to see into their living rooms. Since many people seem to revel in displaying their personal details and identities, I can often infer things about their financial status or personal circumstances just by looking at their cars. Consequently, my home seems less likely to be targeted compared to others in the neighborhood.
Paint buckets filled with nails and screws, tied to some ropes on the bannister
Reinforcing door frames with angle iron and lag bolts. Strengthening the actual doors with steel. Commercial hinges. Glass block windows in the basement. Glock 17.
I’m going to assume that lower tech options come with lower costs.
This post lists many excellent choices, but I haven’t seen any budget security systems mentioned—specifically, those that don’t involve monthly fees.
For around $20, you can get a kit that includes door and window alarms as well as a sign promoting a security system. While it won’t contact the police, it can deter burglars from targeting your property. Plus, if you’re at home, it will alert you to any potential break-ins.
Some may think it’s high tech but I run SmartThings with a few contact sensors, motion, and some bulbs/switches running automation where if any door contact opens between 11pm-530am the lights turn on and flash a few times. Beyond simple and not too expensive. Figured it’s at least something to freak a potential intruder out with and gives me some time to grab the Glock.
Hockey sticks/broom handles cut to fit window/sliding doors inside track, easy and cheap
A dog is a cheap alarm system, deterrent, and kid playmate all in one package.
Backyard/side yard/driveway lighting - LEDs are fairly cheap now, and replacing old fixtures isn’t hard.
Mag-light flashlight by the bed - at least a triple C cell type. Easy to grab when power is out, makes a good weighted club that doesn’t look too suspicious to others
If your window is more than 1 story above ground, a roll-up fire safety ladder is a must in any bedroom
Door lock is a good start
If you’re not going to be in, and it would be clear to any would-be burglar that you’re not in upon inspection. You could place a sign behind a window, or on the door leaving some kind of instruction for a “delivery guy” or a “builder/decorator” who isn’t actually coming.
The prospect that someone is expected to abruptly arrive at the house at any moment is a good deterrent.