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
The best answer I've found is watch your breathing. If its fast and short - LEAVE. You're not ready. When you can calm your breathing and your heart rate, you probably won't be any happier, but you'll have a great deal of self control, enough to be ob<x>jective