Sources: Convicted burglars in North Carolina , Oregon , California , and Kentucky ; security consultant Chris McGoey, who runs crimedoctor.com; and Richard T. Wright, a criminology professor at the University of Missouri-St. Louis, who interviewed 105 burglars for his book Burglars on the Job.

1. Of course I look familiar. I was here just last week cleaning your carpets, painting your shutters, or delivering your new refrigerator.

2. Hey, thanks for letting me use the bathroom when I was working in your yard last week. While I was in there, I unlatched the back window to make my return a little easier

3. Love those flowers. That tells me you have taste … and taste means there are nice things inside. Those yard toys your kids leave out always make me wonder what type of gaming system they have.

4. Yes, I really do look for newspapers piled up on the driveway. And I might leave a pizza flyer in your front door to see how long it takes you to remove it.

5. If it snows while you're out of town, get a neighbor to create car and foot tracks into the house. Virgin drifts in the driveway are a dead giveaway.

6. If decorative glass is part of your front entrance, don't let your alarm company install the control pad where I can see if it's set. That makes it too easy.

7. A good security company alarms the window over the sink. And the windows on the second floor, which often access the master bedroom-and your jewelry. It's not a bad idea to put motion detectors up there too.

8. It's raining, you're fumbling with your umbrella, and you forget to lock your door-understandable. But understand this: I don't take a day off because of bad weather.

9. I always knock first. If you answer, I'll ask for directions somewhere or offer to clean your gutters. (Don't take me up on it.)

10. Do you really think I won't look in your sock drawer? I always check dresser drawers, the bedside table, and the medicine cabinet.

11. Here's a helpful hint: I almost never go into kids' rooms.

12. You're right: I won't have enough time to break into that safe where you keep your valuables. But if it's not bolted down, I'll take it with me.

13. A loud TV or radio can be a better deterrent than the best alarm system. If you're reluctant to leave your TV on while you're out of town, you can buy a $35 device that works on a timer and simulates the flickering glow of a real television. (Find it at faketv.com.)

EIGHT MORE THINGS A BURGLAR WON'T TELL YOU:
1. Sometimes, I carry a clipboard. Sometimes, I dress like a lawn guy and carry a rake. I do my best to never, ever look like a crook.

2. The two things I hate most: loud dogs and nosy neighbors.

3. I'll break a window to get in, even if it makes a little noise. If your neighbor hears one loud sound, he'll stop what he's doing and wait to hear it again. If he doesn't hear it again, he'll just go back to what he was doing. It's human nature.

4. I'm not complaining, but why would you pay all that money for a fancy alarm system and leave your house without setting it?

5. I love looking in your windows. I'm looking for signs that you're home, and for flat screen TVs or gaming systems I'd like. I'll drive or walk through your neighborhood at night, before you close the blinds, just to pick my targets.

6. Avoid announcing your vacation on your Facebook page. It's easier than you think to look up your address.

7. To you, leaving that window open just a crack during the day is a way to let in a little fresh air. To me, it's an invitation.

8. If you don't answer when I knock, I try the door. Occasionally, I hit the jackpot and walk right in.