My mess and clutter was a domino effect, couldn't organize one area unless another area was organized...round and round. I started with a trash bag went through a room and threw out stuff that should have been tossed years ago. Then I took cardboard boxes and filled it with all the stuff that was still good but not for me anymore and I put those boxes out by the curb, posted on freecycle as a curb alert. marked the boxes "free help yourself". Those 2 steps freed up enough space I was able to find room for the keep boxes.

Now I am going through the boxes one by one and organizing them

As for the clothes, can you put them into trash bags and hide them in the bathtub while your landlord is there, same with anything else you need out of site.

Trash
Curb
Hide