Forget guns and cameras, I have a new home defense strategy: soiled diapers.
I'll get straight to the point. In order to best protect your home, just have a baby, feed it lots of food that seems tasty going in but rancid coming out, and then wait for the baby to soil its diaper. When you change said diaper, place it into a plastic grocery bag, then tie the bag up. You might want to double-bag it.
Did I mention that you should be wearing a gas mask while doing this? You can probably find a cheap one at your local military surplus store.
Once the diaper has been placed in the sealed grocery bag, open whatever door or window that you want to secure, and toss the diaper out.
Now, this is important: if you keep your garbage can in an enclosed area, such as a store room or garage, under no circumstance should you be putting the soiled diapers into the garbage can until the garbage is en route to the front of the yard for trash pickup. Otherwise you're just going to smoke yourself out.
Please realize that this tactic, while affective against home invaders, would-be thiefs, Mormons and stray dogs, may also prevent friends and family from coming to your home. But honestly, most crimes are committed by people acquainted with the victim, so it's probably best to keep those people away as well.
If you already own cameras and/or guns, don't despair - you can use those in conjunction with the soiled diapers. If you see a threat in your camera, just get out your gun, then throw a grocery bag with a soiled diaper into the air, and shoot at it as if you were shooting at a clay pigeon. Aim for above the perpetrator's head. The showering shards of soiled diaper will not only be enough to scare the assailant away, but the stench will also help identify the assailant later.
Enjoy your new, well-protected house!