Think of the anger as a secondary emotion to another feeling. Examples- disappointment, feelings of inadequacy, feeling disregarded, helplessness, pain, etc.
When you feel angry, observe what you're thinking at that moment, what happened right before the anger came and then what you are telling yourself at that instant. Then, focus on your breathing (rapid breathing can cause physiological reaction - anger and then the brain adopts this pattern in the future) As you breath mindfully, notice that the anger is actually harming you (it's an unpleasant state of being both physiological and psychological) As you connect the causes for your anger, you can imagine it as a wild animal that you're taming and that you in fact have control over it. It does not rule you and it does not consume you.
It is helpful to keep a journal whenever you can and refer to later on to see all of the steps the mind had taken from the start, mid point and then end of an angry outburst or episode. When you pin point the trigger (initial feeling that brought on the anger) then you address that- examine your judgment- what makes you react so strongly to that?
There are other tools to manage the anger such as hypnosis, bibliotherapy or working with someone in anger management or counseling treatment.
Hypnosis for Overcoming Anger (Hypnotic Empowerment Series)
The Anger Busting Workbook: Simple, Powerful Techniques for Managing Anger & Saving Relationships