You need to chill out and cool down before, sort out the ob<x>jective motives for anger from personal grievances they're not responsible for.
You could imagine you're a third party, your friend or a stranger.
Don't concentrate on the problem as much as finding a solution?
If you yell at them you already lost the arguement
meditation and being able too call on it when you need it. deep breaths. a few seconds on responses too regain composure before answering or asking them. It can be difficult when first learning to control the emotions :S