Organization Of Home – Housemate

I have a Housemate. She is generally more untidy than I am and likes to keep lots of stuff including used glass jars and zip lock bags. In the past when I’ve cleaned out space in our common areas she fills it up with more of her stuff. This bothers me because I like things to have their place and for the house to be in order, but when I open the cupboards they are heaving with stuff. Do you have any tips on how to manage this? I’m keen to clean out my physical surroundings so I can clean up my mind but I feel like this is a road block.