Jeanai,
Firstly we need to catch it , to note it as Anger starts to manifest , only then can we start to counter it.
But we need to prepare to go to war with Anger before we really can over come it. We need to contemplate about how ANGER creates so much problems for us to experience more in the future, by contemplating we are preparing our supplies to wage war on this state of mind called ANGER.
Some things to contemplate on....
i) by reacting with ANGER , we create more karma to experience in future , nothing was purified by letting out our ANGER
ii) separates people and loved ones , once we say something with ANGER we can't take it back
iii) destroys our undedicated virtues
iv) creates bad reputation for us,
v) reinforces our already many negative imprints ,
vi) for me, its useful to think that its is a major weakness to be PRONE to ANGER, as then any situation or person can just walk up and press my BUTTON and I react , i'll be under people and situations control

, as Paris says 'I don;t want to be a stupid boy' ( girl in her context)
vii) anger normally is tied to our expecations not met, but who is the CREATOR of situations that we need to encounter now and later?
ix) Of course being patient will give us a pleasant form in future lives

In the lam rim, you can check out the chapters on karma and in the medium scope in
under the six perfections read about the perfection of patience part .for further reference.
These are my tricks , rehabituating , from conditioned negative to positve habits is something we must strive towards.
I'm not talking about WRATH that can be wielded by skillful yogis and attained lamas or monks.