San Francisco is a relatively safe city. However, like most metropolitan areas, it sees its fair share of burglaries — especially because many houses here are single-family dwellings, complete with back doors, basement windows, and other obscured points of entry. So don't be lulled into a sense of small-town security and skimp on home-safety precautions. Following are some useful means of discouraging an intruder:

• Alarm Systems: If you are not hiring armed guards or building a moat, an electronic alarm system will likely be your most substantial home security investment. Most systems operate either through magnetic sensors that connect between two corresponding points or through photo cells that project a beam of light between two different points — e.g., between a window and a window frame. Anything interrupting the magnetic contact or passing through the light beam will activate an audible alarm. The technology and cost can be intimidating, so keep these guidelines in mind when shopping for an alarm:
  
  
  • Get estimates from at least three or four companies. Ask for recommendations from your homeowner’s insurance company and local police, as well as other people in your building or on your street. You should also consult the National Burglar and Fire Alarm Association (NBFAA) Web site for names of members in your area. Its main offices are located in the Dallas, Ft. Worth Metroplex at 2300 Valley View Lane Suite 2300, Irving, Texas 75062, Toll Free: (888) 447-1689.
    
    
  • Request that estimates cover all points of entry to your home, as well as the perimeter of your yard. Consider your lifestyle: if you are often away, and/or you have expensive items in your home, you may need a more sophisticated system. Ask for information on higher-level options, such as heat or motion detectors and automatic police notification. (However, be aware of the potential nuisance of false alarms: you’ll not only annoy neighbors and the police, but possibly set yourself up for a fine.)
    
    
  • Because costs can vary widely, make sure that estimates are clearly itemized so that you can easily compare prices. Look for hidden charges, such as installation costs and monthly fees. Finally, be sure to inquire about warranties and customer references. Reliable companies should be happy to provide both.
    
    
• Deadbolts: You should have a deadbolt on every exterior door, as well as entrances to the garage and basement. Installation might involve nothing more than committing to a do-it-yourself weekend project. The bolts are inexpensive. Also, remember to keep all doors leading to and from the garage locked. If not, the garage could provide a discreet place for a burglar to pick the lock to your house.