I had severe anger issues growing up, and the only way I was ever taught to deal with them was deep breathing. For some reason, deep breathing just triggers me to get angrier. But it's the only coping skill I ever got taught for it. Here's a few better ones.
Go and exercise. Get all of that energy out and away from the people you love.
Get a hang of when you're winding up to a rage and learn to tell people that you need to step away. I will warn you that the first time that someone refuses to let you go once you learn this skill will spook the hell out of you if you don't have a backup skill, so figure out ahead of time what you're gonna do if they won't let you leave.
Learn to set boundaries. One of the best things I ever did for my anger issues was tell people that I can't deal with people stealing food off my plate. Second best was when I'm mad, telling people not to touch me. I spook easily when I'm already angry.
Get a pack of pencils and if nothing is working, break one. Sometimes you really do need to break something in order to feel better, and pencils are cheap.
Don't cook with a knife when you're mad. If you get too much adrenaline, the knife can slip and hurt you.
If you have anger issues that pop up without any seeming reason and frighten you, I would strongly recommend going over the situation and over your mental health. If there's anything consistent with a mental health condition or with something particular happening to trigger it, seek to eliminate the trigger or treat the issue. Depression, anxiety, trauma, you name it, it can probably present as anger issues under the right circumstances.
Some quick notes for people without anger issues that want to help someone who has anger issues:
Fear transmutes into anger really, really well if someone's fear response is "fight". One of my guesses for why so many men have anger issues is that we're told we're not men if we have any other response to fear. However, this issue is far from exclusive to men.
Don't box people in when you're arguing with them or soothing them. If someone is backed up against a wall and upset, then getting closer to them without permission is a bad call for your safety and for their soothing, because that removes the ability to get away from you. Ask before getting close. This goes double if someone is injured or otherwise vulnerable.
Teaching angry people that are distressed about being angry the pencil trick on the spot is really easy and works more often than you can think.
Respect people's requests and boundaries. A lot of people think that some of the boundaries I set up are silly or that once we're pals, they can ignore them. No, because a lot of my boundaries are related to trauma, and crossing them will trigger me and bring up my anger.
All of this goes for children with anger issues as well. I was a child with anger issues, and a lot of disrespect for my boundaries and needs was because my anger was dismissed because I was a child. Respect children's anger.
Walking on eggshells is not and will never be a good way to treat anger issues. Recognizing that people with anger issues deserve to have their boundaries respected and to be treated like human beings is.
An end note: Anger issues are not the same thing as being abusive, because emotions are not abusive. Someone with anger issues can become abusive if they take them out on people, but so can someone with suicidal thoughts who takes them out on people. The issue is targeting another person in order to feel better, not having a mental health issue.
An end note for people with anger issues: It really can get better. You can find coping skills and perhaps meds that help cool you down and settle you. You can find people that will accept that doing that one weird thing spooks the fuck out of you, and will let you leave if you're scaring yourself. You can gain control of yourself without shutting down emotionally. It's achievable.
