My 2 cents:
Home defense falls into two categories: convenient and serious. At some point, we decide to live with the risk rather than the cost and hassle.
Serious:
Getting a dog, vet bills, training it, loving it, making arrangements for it when you're away.
Getting a gun, training with it, having it available when you need it and keeping it safe when you don't have it with you.
Installing a security system and paying a monthly bill to have ADT or somebody monitor it.
Putting up a fence if you don't have a fence, putting up a 6 foot fence if you have a 4 foot fence, keeping the gate locked.
Beyond that, a 'Master Lock® Dual Function Door Security Bar' ($20 off the Lowes webpage) will slow down somebody from kicking in your front door, if you want to bother setting it up every night.
Likewise, a 'Door Jamb Armor Universal Doorjamb Combo Set 2-3/4" Backset' ($120) will make your door somewhat more resistant.
Replacing your house's flimsy inside doors with exterior doors (and door frames). Or at least putting a key'ed door handle on the door that goes from your garage into your kitchen and remembering to lock it (and then saying 'darn it' when you forget and lock yourself in your garage without keys); ditto for the door to the basement stairs if you have a split level.
Convenient:
Putting up a fake beware of dog sign or ADT sign.
Solar powered walkway lights (so you don't have to run wires, and they work when the power goes out).
Drapes/blinds/shrubs/external lighting so people can't see into your house easily at night and figure out where you are & aren't.
Closing doors at night, so an intruder doesn't immediately know which way to go (i.e. is that the bathroom or a closet? Which is the master bedroom?
If you live in the suburbs, keeping your yard free of 'attractive nuisances' like the kid's bikes, yard gnomes, etc. that might entice punks & vandals to notice your property and wander toward your house.
If you park on the street, not leaving cell phones, CDs, cash, or handicap hangtags visible in your car/truck.