Just like a chain is no stronger than its weakest link, your home security is no stronger than the easiest and quietest way to defeat it.
Look at your front door, the most used and most likely entry point for anyone wishing to enter your home for either good or ill. Is it a strong solid door without an breakable window near the lock? A good first step, if properly locked crashing through it will at least be noisy.
Check the door on the left. A parole office and police officer used a battering ram to try to enter this apartment, but gave up without getting it open. It was a standard commercial apartment door set into a matching steel frame. It held, the deadbolt did its job. The attempt was abandoned by them, However just a few days later the fugitive entered the apartment without a key by climbing to the second story balcony and using the sliding patio door.
The neighbors heard the Police and Parole office but no one noticed the criminal.
A standard sliding patio door is about the easiest point of entry on most houses. it is often away from the public view, behind the house, shrouded by shrubs and fences, and not often lit, or even locked. The locks are usually weak and often don’t work well at all. Even one that is in good shape will usually yield to a simple pry-bar. There are blocking bar and other types of add on devices that can help.
How are the locks on your outside doors? The old standard locking knob is better than no lock at all but not much, it will stop someone from just walking in but a pry-bar or screw driver or even a swift kick will usually allow a criminal access. A deadbolt is somewhat better but only against someone without the initiative to make or buy a $3 bump key. Most standard entrance locksets and deadbolts are easily and quietly defeated with a bump key. Forget what you’ve seen on TV about people picking locks (like Magnum “don’t look at the dogs, work the lock!”). A bump key works by basically inserting the bump key like a regular key, pull it out a bit, lightly twist the key with one hand and bump the key back in. The lock is defeated. Hardly a noise, in as little as a second, taking no more time than you usually take unlocking it with your own key.
How do you safeguard against a bump key? If your key looks like this one, the lock is vulnerable to a bump key. That includes deadbolts and door knob locksets. The same company that sells the bump keys will sell you an inexpensive piece that will mount inside a deadbolt that will prevent any key opening it from the outside but that does nothing for you when you are not there, and a bump key leaves no visible evidence outside that someone has entered, you cannot know that there is no one waiting inside when you use your key to open the door.
One solution is to replace the deadbolt lock with a keypad which has no key (I do wonder about getting in if you forgot the code or the battery goes dead). Another is to install a bump resistant lock, here is a video by Kwickset about their smart key tech vs their competitor (there is another youtube that shows how to defeat the Kwickset in 10 seconds so the technology is not perfect). Even Kwickset’s web page notes that no lock is 100% unpickable.
There are lock replacements that work with a cell phone with or without a key lock in combination.
The best you can hope to do is make it difficult or time consuming or noisy. Backing up any lock with a security – alarm system can help by making it more likely to be noisy or alerting someone. Short of hiring guards 24-7 to guard your home, there is no way to assure that no one will break into your home. Even with a perfect unbreakable lock on a perfect door, they could break a window or take an axe and crash through the wall. The best you can hope for is to discourage the person, make them look for softer targets.
There are two schools of thought on placing an NRA sticker or a sign saying “we don’t call 911” and a picture of a gun. It may deter thieves when they suspect someone is home but may attract them if they know the place is vacant.
So just don’t make your place easy to target, try to force an intruder to bring more tools, make more noise or spend more time and make it obvious what they are doing or what they have done. And most important – lock the locks and don’t hide a key.