There is more truth to the saying that a man's home is his castle than you think.  Castles are defended in depth.  What I mean by that is that they didn't start and stop at the wall.  Castles weren't designed to allow the opposing kingdom to march to the wall, bust through, walk through the garden and kill the king were they?  No. 

Castles were usually built high on a hill.  This was done for a few reasons - of course the view is better.. But also it makes it harder for the attacking army to climb to the top undetected and without getting really tired. 

Once up the hill there was often smaller walls, thorn trees and sometimes even a mote.  Of course, the walls were thick stone and the gate was heavy and solid wood.  The knights that defended the castle had great visibility all the way around the castle. 

Once inside, if they made it that far, the attacking army would have to fight their way to the king, who was usually in a heavy stone building located in the center of the castle court that was just as heavily fortified and defended. 

    Now, that was an over simplified version of how things were done when we built castles.  Most towns and cities frown upon mote building and have developed some kind of law to prevent it.  But what can you do?

Defend in Depth

Think of your house like a castle - it should be more like an onion than an egg.  Start at the street and work your way in. 

Outer Edge

Fence - From chain link to white picket their a good idea.  They will add seconds to any approach, plus limit the avenues a person could easily enter your property.  They don't have to have razor wire to slow a criminal down.

Plants - not only do they make you yard look better, but they can make your house safer.  I don't suggest thick shrubs (their easy to hide in).  Try rose bushes or a variety of other plants to deny these spaces and avenues of approach.

Lights - Motion detector lights should be installed along likely avenues of approach.  The motion detection should reach out as far as possible and the light should deny the bad guy any hiding areas.

Inner Edge

Windows - Install security windows.  Couple paned with Mylar or some other blast/shatter resistant coating.  Bars are great but they can be a little unattractive.  Consider all windows!  Remember you may have windows into your basement or 2nd floor windows that can be easily climbed to.

Doors - consider reinforcing your doors.  When your house was built the contractor used the minimum material possible to meet basic building codes.  It doesn't take much to get through most doors.  Remember also that the lock and knob you replace is only as good as the door and frame around it.  Also, consider a lock that the requires a key from both sides if there is a window near the lock.  It won't do much good if they can break the window and unlock the door.

Blinds - It's a lot less tempting to steal what you can't see. 

Mail Box - Don't put your full name on your mail box - a thief can look you up in the phone book and call to see if your home.

Inside

Alarms - Even if you don't have one consider putting the sticker on your doors and windows.

Guards - OK maybe not knights or even Barney Fife, how about a dog?  They are great alarms, plus they just might chase the guy off with a hole in his pants.

Safes - Secure anything really valuable in a safe deposit box in a bank - there insured and less likely to be robbed to begin with.  If you get a safe for in your home make sure it can't be carried away.  It should be chained to the floor if it's less than 500 lbs.

Safe Room - find some place in your home where you and your family can hide until the police can get to you.  Read more about home invasions here.

Weapons - Although I don't suggest a firearm I suggest that you get something to defend you and your family with.

Neighborhood Watch

There are a variety of programs available depending on where you live such as the National Neighborhood Watch Institute.