For digital, I use Google Drive, with rough organization of Taxes/2021, Taxes/2020, ..., Health, Family, Notes, etc. Don't obsess too much, you rarely go back in time so it's OK to keep it lightweight and optimize for the "now" when inserting and spend that little extra time searching later when retrieving.

The exception are things that are too tedious to scan (50+ page mortgage doc), are required to be paper for legal reasons (birth certificates), or sentimental items. Those are surprisingly few, and go into a hanging-folder plastic tub that has a waterproof gasket on the lid.

Most damage from house fires is the water from the firehoses, so it's important to protect from water damage first, then worry about fire damage if you keep your documents at the top of your home (attic). I store my document tub in the bottom of my closet, so it's relatively safe.