Preventing Identity Theft

A friend of mine recently went to the bank to open an account and was told that someone had already opened an account with her social security number a couple years ago, unbeknownst to her.  In the process of investigating this, she also discovered that a man named Juan was using her social security number in medical claims in Texas.

As you can imagine, she is trying to look into identity theft protection, and so I am creating this project to ask for your tips.

What do you do to protect yourself?  Do you use any services (such as LifeLock)?  Any you would recommend or advise against?

I'll keep this project private for once in case anyone is shy about sharing their story.

Thanks much!