What do you do to return the rent deposit/caution money when you are moving out of the apartment?

To all my fellow renters out there, I need some advice. This is the fourth time I've moved out of an apartment and didn't get my deposit back. I'm wondering if any of you have found smarter ways to handle this situation. Are you using smart contract platforms, shared Google Drive, Gmail, or perhaps lawyers? Any insights and tools would be greatly appreciated.