Like Wasp said. There are the proffesionals that have targeted your place because they know what you have. And there are the randoms. The proffesionals usually know what you have because some one talked about it. So low profile about what you own is best deterent there.
Randoms are easier, just by making it hard. Full fence around your property with locked gates. Helps if you like living in a compound. A couple of mastif cross gaurd dogs that are bred specifically for stopping people help as well.
http://www.trubluebandog.abcalert.com/ http://www.boerboelaustralia.com/info.htm Design and build your own front gate around a closed shackle padlock that can't be accessed with cutting tools. Keep it closed and locked 24/7 even when your at home. Some people only close/lock them when they go out, if someone is scoping your property it's like a signal that your not home.
Lock all your bikes except one or two that you can afford to loose. They're your decoy bikes. They'll go for the quick and easy. Buy all your locks from an online wholesale locksmith in the U.S. for about one third of the price here, and order them all keyed alike so you only need one key.
The best security is to have someone home, so move your aging inlaws in.
A mate of mine, after having his bike stolen built a strong room inside his shed to park his bike in. Worked when he got hit again two years later. All they got was his helmet and jacket.
Another good deterent and this is my favourite, is to put crazy hand painted signs all over the front of your place with religious rants all over them, throw a few warning ones in for good measure. Then dump old junk everywhere. You will be known as the madman, and your place will look like crap but it will keep people away. No one wants to mess with what they percieve to be a physco, because they can't predict your behaviour.
Those farm cameras or hunting cameras are good if you want a collection of pictures of some blokes with hoody's over their heads wheeling your bikes away.
If your bikes do get stolen, don't beat your self up over it. Move on and put it behind you. I had a mate who's house got done over. It ate him up, destroyed his marriage and ended up having a heart attack and dying over it all, he was 37. At the end of the day you can't take it with you. Take it on the chin like a bad tax bill and use the anger in a positive way to drive you to a better life.