Having had to sort out my dad's house and stuff when he passed 4 years ago, I'd say:
Declutter! You don't need 50 years worth of every bloody bank statement/reciept/letter that you've ever received, "just in case"! Especially not mingled in with all the relevant, up to date stuff. Or several semi broken kitchen appliances that you might get around to fixing, or an entire spare bedroom and garage/carport full of duplicate tools/nuts/bolts/screws/electrical components/light fittings etc etc.
Keep all important documents together, along with a list of active bank accounts and pensions. Do not hide the house deeds under the tray in the cutlery drawer, and please let your offspring know which solicitor has a copy of your will, not just a vague "one in town".
Write down passwords and keep it up to date.
Write a list of people that will need to be informed, as opposed to a 50 year old address book with out of date passwords.
Have a plan for what you would like for your funeral in regards to burial/cremation and any particular music.
As you can tell, it was hell sorting my dad's stuff 🤣
I'm in my 40's and making a big effort to get my ducks in a row so my son doesn't have too much to do when my time comes. I'm also trying to future proof my house, as I'm already physically disabled, so I've had things like a downstairs loo fitted, the kitchen remodelled with things at the right height/somewhere to sit to do food prep etc. I've swapped my bath for a walk in shower with a built in seat and I'm planning to get a stair lift fitted, or at least make sure I ring fence enough money to do this at a later date, so as I can stay independent as long as possible.
I've bought a fireproof document box where the house deeds/car stuff/passports etc are kept, plus a ring binder with account numbers and everything filed in.
I'm also going to take out a prepaid funeral plan, once I've shifted some money round to pay for it.
I'm just trying to streamline as much as possible. Hopefully, I'll be here for a long time yet, but I've lost a couple of friends my age recently and that has really made me realise I need to be prepared a bit better.