Lol, I posted a thread a bit like this the other day and have been making a bit of an effort. My 4yo is in an especially trying stage and is doing a lot of screaming and shouting and threatening and demanding. Except I think some of it is from me 
This is what I've been doing so far:
- When DS2 (4) is asking endless questions, or annoying his brother on the tram, I engage him in a game like I Spy.
- When DS3 (nearly 2) is making a horrid screeching noise I start singing wheels on the bus at him. He insists that I do several rounds but it's better than the screeching.
- When trying to engage them in instructions or they are getting wound up about something, I go right down to their level and take a big, obvious deep breath - apparently this triggers mirror neurons and they will breathe too. IT WORKS!! It doesn't instantly calm them down but it takes them down a notch or two, which helps a lot usually.
- Making an effort to try to moderate my voice and make requests in a low, pleasant, calm voice, rather than barking them because I'm already annoyed.
- Likewise when I want 4yo to stop screaming/shouting I make my voice really low and calm to model what I want.
I've been doing the course on Coursera called ABCs of Everyday Parenting. Some of it is patronising/obvious but there are some useful tips. And honestly though I was watching it thinking well duuuuuh of course you should ask children nicely to do something instead of being an army drill sergeant, when I started to listen to myself I realised that I quite often get irritated and let that irritation colour my tone or volume.
I've also been really into Conscious Discipline by Becky A Bailey recently after listening to her on a couple of podcasts. That's where I got the deep breath/mirror neuron tip. They also have this thing called breathing icons, so I googled that and found a youtube video which shows you how to demo 4x simple breathing exercises for children and a PDF which you can print out with the breathing icons on them. I started doing them just for fun with the 1 & 4yo and they now ask to do them all the time. So we are doing this just whenever we want to when we are already calm, and then I'll try to suggest them when they are not calm. I printed the PDF and stuck the icons in the living room and bedroom, which is where we spend most of our time.
I have this book called When Your Kids Push Your Buttons which I bought when DS1 (now 14!) was 3 and driving me absolutely nuts all the time - I keep getting it down off the shelf but haven't read any more of it currently.
I started taking some iron tablets, in case I'm anaemic. I've been pregnant and/or breastfeeding since December 2017 - so this wouldn't be totally unheard of. This seems to be helping a lot but I'm unsure whether it's the iron or whether I was just pre-menstrual 
I also tried to notice exactly what triggers the aaaaaaaargh RAEG and one of them is when people are stupid/wrong on the internet, and then even more so when other people agree with them. So I have been avoiding the places on the internet where I'm likely to encounter wrong people. The vast vast vast majority of microcontent winds me up (instagram, youtube shorts, FB reels) and there are certain topics that are likely to trigger this too so I've stopped clicking on threads like that on MN. I did actually hide AIBU for a bit too, though recently I unhid that.
To replace this I've joined a couple of charming groups on FB about doll house furniture and tiny things, and I rearranged my reading list so I have something to read and I have some puzzles and I like building houses in the sims, and I'll queue up some series to watch. I feel like this all helps avoid the doom scroll.