Just like many others in digital marketing, Shira Abel took an open approach to her social networking, accepting most friend requests on the location-based service Foursquare ( -- until a "friend" she didn't know turned weird.

"He asked if we could meet," she said. "I told him I was married and not interested." But he kept asking. At her next check-in, the stranger asked Abel where she lived, "which is when I unfriended him," she said.

Location-based services have become a growing arm of the social media landscape. To keep up with Foursquare -- where people earn badges, points, and special status for visiting restaurants, bars, hotels and other businesses -- and its competitor Gowalla (, the review site Yelp ( has added a check-in feature (instead of becoming mayor, you're the Duke or Duchess if you're a repeat customer). You can geotag your tweets on Twitter ( if you want. Even Facebook ( has a "places" feature that shows your friends where you're at.

But as Abel's experience shows, using location based services -- especially when you're on vacation -- can be tricky business. It's one thing to announce to your vetted Facebook network that you're heading to the beach. It's another to give the world your exact coordinates.

After the stalker-like incident, Abel revamped her Foursquare strategy: She'll only update her check ins when she's leaving a place. And she won't friend anyone who she doesn't know.

If you'd like to use Foursquare or another location-based service while you're traveling, here are a few privacy tips to keep in mind.

Understand the differences between services. As I said in a recent column about Facebook privacy, people run into problems with social media when they don't understand how the different services work.

Twitter allows anyone to follow you or search your tweets; don't turn on geotagging unless you're prepared to accept that risk. The service understands how risky its Tweet With Location feature could be and specifically tells users to "be cautious and careful about the amount of information you share online." Twitter allows you to delete all location information with a single click and you can opt out for specific tweets.

Like Facebook, Foursquare requires you to accept a friend request before people can see your check-ins. But unlike Facebook, you can't sort people into categories or control privacy settings. So it's more public -- and thus more open to abuse.

Choose your friends wisely. Because you can't control its privacy settings, it's better to restrict your Foursquare friends to people you actually know. Don't worry, you'll still be able to share your latest mayorship: Foursquare makes it easy to post your badges and check ins directly to Facebook, if you wish. That's one way to control exactly which of your friends can see where you are.

Check in after you leave. Security conscious, yet still want to earn points and badges? Wait until after you've left to check in. That way, you'll still get the credit, without inviting stalkers.

Post off the grid. Heading to the doctor's office? You can make your check-in "off the grid." So you'll still get points without telling the world about your colonoscopy.

Don't add your house on Foursquare. This might seem like a no brainer. But you'd be surprised how tempting it is to add your home as a Foursquare location (hey, at least that way, you're guaranteed to be the mayor of somewhere).

Instead, Abel checks into her city when she returns from a trip, instead of her residence. "No need to show stalkers or anyone else unsavory for that matter where you live," she said.

Travel journalist Chris Gray Faust dishes up travel tips on her award-winning blog, Chris Around The World. She's also the author of the Philadelphia Essential Guide, an app for iPhone and iPad.