Make sure that all doors to the outside are metal or solid (1 3/4" hardwood).
Make sure doors have a sturdy deadbolt lock, with a minimum of 1 1/2" bolt.
Always lock up your home when you go out.
Secure glass doors with commercially available bars or locks.
Make sure all windows, especially at ground level, have good locks.
Make sure all entrances are well lighted.
Trim bushes or trees that hide doors and windows.
Don't hide your house keys under the door mat or in a flower pot.
Keep a written record of all the furniture, jewelry, and electronics. If possible, video record your property and note serial numbers and other helpful information. Place these items in a safety deposit box or in a secure place.
When You Go Away
Ask a trusted neighbor to collect your mail and newspapers, and offer to return the favor.
Leave word about when you're leaving, when you'll return, and how you can be reached in an emergency.
Put automatic timers on at least two lights (and possibly a radio) to help your home look and sound lived-in.
A watchful neighbor who looks out for you, as well as themselves, are a front-line defense against crime.