Here's a quick tip for you; we do this every night.
Shut your garden gates
You've paid for a lovely set of gates to your driveway but the only time when you actually shut them is when you're on holiday. How much of a clue do you think is there for the observant opportunist thief?
Take the time to shut the gates when you get home. Once you've established the habit, you'll feel uneasy when you don't do it. It's the same when you put on the seat belt in the car - after a while, it doesn't feel natural when you forget to do it.
Thieves like an easy getaway route; if you've taken the time to shut your garden gates, it's much more likely that you've got your doors and windows locked, making them go look for an easier target.