Here is a AAA article on securing your house for vacation:

First, invest in a deadbolt that requires a key to lock. Make sure that there is at least a 1-inch draw into the door jam. Simple, spring-loaded door locks are easy to pick and offer almost no security. Also, don’t forget the sliding doors. Place a metal bar or a wooden dowel rod in the door track. Better yet, invest a few dollars in a slide lock.

Every effort should be made to give your home that “lived-in” look. Leave blinds and curtains in their normal position. Set an automatic timer so lights periodically turn on and off. Consider a timer on the radio.

Ask a trusted friend to check on your house regularly. Make sure the friend knows how to reach you in case of an emergency. Give him or her a key to your car in case the vehicle needs to be moved. Also, inform your friend of anyone who may be visiting your home while you’re away.

Consider storing your valuables in a safety deposit box. If you choose to keep them at home, choose two hiding places. One should be relatively easy to find and the other difficult for an intruder to locate. Hide a small amount of cash and a few small items like costume jewelry in the easy-to-find place. A burglar may assume that all valuables have been found and stop looking.

If you’re traveling for several weeks, arrange for lawn service. Keep shrubbery trimmed around windows and doors. Don’t give a thief a convenient place to hide.

Ask your friend to pick up your mail each day. If that’s not possible, have the post office hold your mail until you return. Temporarily cancel your newspaper subscription. Several days’ worth of newspapers in your driveway quickly reveals an empty house.

Never leave spare keys under doormats, flowerpots, or other “hidden” places outside the house.

If traveling by air, don’t expose personal information on your luggage tags. Use your business address or tag covers. If a thief reads the address on your luggage tags, he may assume your home is unoccupied.

Contact your local police and request a daily drive-through of your neighborhood.

Upon return from your vacation, if you notice the front door ajar or any sign of forced entry, do not go inside. Immediately call the police for assistance.