I know it's a subject I refer to quite ofen but the fact is that it's so relevant for our well being. The site PsychCentral has a very good summary of the main points. Have a look at
http://psychcentral.com/blog/archives/2009/09/26The main "steps" are:
Step One: Become Aware of Acute Stress and Toxic Situations
Step Two: Create a Self-Care, Personal Renewal Program
Step Three: Surround Yourself with Four Kinds of Friends
Step Four: Recognize and Concentrate On Signature Strengths
Step Five: Examine Oneself and Accept Shortcomings
Step Six: Practice Mindfulness and Meditation
Note the need for a balanced circle of different kinds of friends!