Tens of millions of photographs are posted online and rarely is any harm done. But,
you always have to think before you upload, especially images of your children and or photos that give obvious clues about where you live.
Stephen Balkam, CEO of the Family Online Safety Institute in D.C.  suggests that parents always use the privacy setting on social networking sites such as Facebook, which allow you control who sees your pictures. 
Think twice about posting a picture  if it shows a revealing body part (no matter how innocent) or reveals your location. Kimberely Isbell, a fellow at the Berkman Center for Internet and Society at Harvard University, offers these additional tips:

Only post low-resolutions pictures, which do not enlarge well, or include a digital watermark on your photos.

Consider licensing through Creative Commons.org, where you can specify whether a photo can be used for commerical purposes. You can note that if a photo is reused, it must be attributed to you.

Flickr has a mechanism that prevents an image from being copied. Although most hackers can crack this type of software, it will deter those looking for an easy image to grab.

Learn how to use Flash to imbed your photos in a blog, rather than using jpeg images. It’s harder to copy images from Flash.

Create a very unique file name for the photos you post, and you can periodically search Google images for those file names.

“Anything you can do to make it harder to copy the photo,” will deter the majority of those likely to swipe a photo, she said.