Start with safe walking.
Nothing on stairs,
nothing to trip on from bed to bathroom.
Like Tillie suggests keep taking trash bags out where the can be taken away.
Find out when heavy trash pick up is available . Most cities have a day where couches and other things can be taken for free.

Tillie and the others have much more experience than I do .

Sleeping area.
Hallways
Bathroom
Kitchen fridge sink trashcan
Storage area.

Check the smoke detectors and furnace filters.
Also find or get a fire extinguisher.

Then I would go 1 room at time .
One at time from the front door to the back door.
Then prioritize.

I wish I could advise about the dementia. I know the paranoia can be heartbreaking to witness. If she wants to keep something. Let her keep it. No matter how you feel . Let her feel good about keepin things when ever you can.

Secure medicines. As if you may get some help you don't want anyone accused of taking meds that don't belong to them

Secure the legal documents and financial Information

Keep us informed.
Let us know as much as possible.

Hey there and welcome! Getting the trash together is a very satisfying start. It can feel daunting but sometimes you just have to plow through it. Also, I always like the idea of making the beds--clearing off the junk, putting on clean sheets and knowing no matter what, there's a good clean neat space to lie down.

We are here for you. We will help you through this.

Hi Allison 🙂

Here we always say to grab a trash bag and fill it with everything that is obvious trash or broken.
Take the bag out to the can or dumpster.

Another way to start is to pick a small room, like the bathroom, and work in there for 5, 10 or 15 minutes at a time until it's all clear.

Tell us more about your situation so we can better suggest things.