Six things that lead to the abandoning of ill-will:
1) learning the meditation on loving-kindness,
2) cultivating meditation on loving-kindness,
3) reviewing ownership of kamma,
4) abundant reflection,
5) good friendship, and
6) suitable conversation.
— from the AN commentaries, translated by Bhikkhu Bodhi
The last suggestion on this list recommends “suitable conversation” as a way leading to the abandonment of anger. It may be that if we create the habit of only speaking in accord with the Buddha’s guidelines, anger will no longer arise. Until we get to that point, we can start by abstaining from unsuitable conversation, even when we feel angry; that is, not saying anything when we have nothing beneficial to say. Instead we can breathe, feel the sensations present, and make note of the phenomena arising and passing in our bodies and minds.
It must be acknowledged that restraint in speech may not feel “natural” to us. We are so accustomed to speaking our minds without a filter, it can seem awkward to set our word-making to a slower, more reflective speed. We have to ask ourselves whether it’s worth the effort. Some wise words on the subject are here:
From an essay titled Right Speech, by Thanissaro Bhikkhu
As my teacher once said, “If you can’t control your mouth, there’s no way you can hope to control your mind.’ This is why right speech is so important in day-to-day practice.
Right speech, explained in negative terms, means avoiding four types of harmful speech: lies (words spoken with the intent of misrepresenting the truth); divisive speech (spoken with the intent of creating rifts between people); harsh speech (spoken with the intent of hurting another person’s feelings); and idle chatter (spoken with no purposeful intent at all).
Notice the focus on intent: this is where the practice of right speech intersects with the training of the mind. Before you speak, you focus on why you want to speak. This helps get you in touch with all the machinations taking place in the committee of voices running your mind. If you see any unskillful motives lurking behind the committee’s decisions, you veto them. As a result, you become more aware of yourself, more honest with yourself, more firm with yourself. You also save yourself from saying things that you’ll later regret…
In positive terms, right speech means speaking in ways that are trustworthy, harmonious, comforting, and worth taking to heart. When you make a practice of these positive forms of right speech, your words become a gift to others. In response, other people will start listening more to what you say, and will be more likely to respond in kind. This gives you a sense of the power of your actions: the way you act in the present moment does shape the world of your experience. You don’t need to be a victim of past events.
(full essay here: http://www.accesstoinsight.org/lib/authors/thanissaro/speech.html)