I have no idea what to tell you.
From what I have seen, people stash inportant items everywhere, all mixed in with everything.

What cleaning crew is coming?
A professional extreme cleaning crew knows what to look for when decluttering and has boxes set aside to place inportant items in as they find them.

We have "permission" to clean up but want to gather important items and paperwork first before cleaning crew comes. How to we organize really important things--jewelry, financial documents, etc. and "important" things that have accumulated over decades versus actual garbage? We are overwhelmed and don't know where to start.