"We call 'em 'walking 251s,'" says District Police Sgt. Donald Blake of people who appear to be likely crime victims. (A 251 is the number of the form that documents the offense.)

"You can pick 'em out. Sometimes it's because they look out of place -- like they don't belong in that area. You could call it body language -- something in the way they move that makes them look like somebody who's going to get it."

Chances of becoming an assault victim increase during the holiday season, notes Blake, "because everyone -- crooks, too -- needs extra money." To avoid becoming a victim, crime prevention experts advise:

Always think about where you are going and who is in your path of travel.

Have your keys ready and look around before entering your car.

Develop peripheral vision. Says self-defense instructor John Martin: "Instead of staring down at your feet when you're walking, keep your eyes and face alert."

Walk confidently at a steady pace. "New studies show that people who are aggressive," says Mary Lystad, chief of the National Center for the Prevention and Control of Rape, "are less likely to be attacked."

Test your reactions. "Police officers often prepare themselves for crisis situations by playing a game," says Arlington police officer Gregg Kurasz. "As you're walking along ask yourself what you'd do if someone approached you and asked for your wallet or tried to grab your purse.

"You don't have to get fearful about it. But then if the situation occurs, you'll already have a game plan and course of action in your mind."