Well a big katana worked for me but thats not to say its foolproof ;P
I'd get a 7 foot fence, automated gates, motion sensor security lights, computer controlled rollerwindows, and rollerdoor for the car, a metal security door and a steel main door with a 6 pin deadlock, a big dog called brutus, motion sensor sentry guns like in the movie aliens, electrified razor wire, a moat filled with acid, laser guided intercontinental ballistic missiles with multiple independant re-entry vehicles with resolution up to the square foot, a naval quality railgun powered by my own nuclear reactor, ablative armour on the walls and roof, landmines under every square foot of lawn and razor blades attached to the branches of foliage, 240 volts rigged up to the metal parts of the house etc etc
yeah it'd cost a bit but they'd think twice... you'd hope...
-D
EDIT - And when I'm feeling really insecure, I take to the air in a helicopter gunship.