Surrounding yourself with safe people is one of the big things my counselor talks about. People aren't really born with the ability to screen who is safe (i.e., not emotionally harmful) and this book has been helping me. It's written from a Christian perspective but I think these apply to people of any religious or non persuasion. Some of the gist is in this article by Henry Cloud:
"Have you ever wondered why some relationships seem to lead to growth and happiness and others to pain and injury? Have you ever had the experience of meeting someone, finding them attractive and charming, trusting them in some way, and then later were hurt very badly by them? Or, worse than that, have you done that more than once with the same kind of person?
It would be nice if we could all answer "no" to the above questions, for that would mean that we would have avoided a lot of pain in our lives. And it would also be nice if those realities did not even exist so that we did not have to think about them. But the truth is that relationships can have the power to save our lives, or the power to ruin them. . . .
Learn what traits are helpful and hurtful in people . . . The important thing is that you learn to recognize things like:
• inability to connect
• control issues
• domineering traits
We all need to know what it is that we are looking to confront and to avoid. If you are going to give your heart to people and trust them, you have to know what you are looking for. Search the Scriptures and other materials that teach about relational patterns."