Your local government should have leaflets on home security, but be careful as barbwire (in the UK) can work against you if the trespasser is injured.

I considered rigging at least one 'rape alarm' to a door, or even as a trip-wire in the house so that it would go off.

I think having a dog is probably one of the best but you need to go further than that for good protection (when you go for a walk, on holiday)

Some people have gravel around their property, movement-sensitive lights.

Don't give them anything to steal! have a cheap safebox hidden somewhere, screwed in to a wall for pp, cash, etc.

The things people will steal are jewellery, laptops, SatNavs (GPS) and other things are are light and small- which makes these easier to hide.