I've only got two kids so perhaps my life is less hectic than others but these are a few things I do to avoid chaos.
Number one rule is to have minimal clutter.
When my boys have their birthday and also after Christmas I gather toys that are barely used to make room for the new ones. (I sell them). My boys are in the habit of packing up one activity before moving onto the next - and messy activities (craft, play dough, puzzles) are all stored up high and they need to ask to play with that sort of stuff.
Secondly - routine!
Just get in the habit of whatever it is you want do
For me it means each week I change sheets, do my massive clean (small ones throughout the week) meal plan, I have a magnetised list on my fridge (as soon as I run out of something I write in in there so I don't forget, I also sit down on a Sunday night and write anything else I need for the week). I think I'd hyperventilate at the shop without a list!! Lol
Also my very last tip is to pop everything into my phone. I have a shift calendar app that I plug any appointments into, days my boys go to their dad, times I need to remember (eg- ringing about something first thing Monday), Parties, school term dates. I then set alerts so my phone reminds me of these appointments - one a couple of days before the event and one a couple of hours before.
I have a dreadful memory and find that if it's written down I can go about like a normal organised person in disguise