Two tiers, and never on the internal drive
'This is where you hold all of your active footage' - one SSD, one project.
Nothing lives on the computer. One SSD holds the footage of the project currently being edited and nothing else, because SSDs are fast, have no moving parts and are less prone to sudden death - at a price. When the project finishes, the footage moves to a larger, cheaper HDD for the long term and the SSD empties for the next job. Backups are deliberately selective rather than universal: only footage that genuinely matters - personal milestones, recurring commercial clients - gets a second copy on a separate drive, which is a more honest policy than pretending everything will be mirrored. Drives are labelled in the order they were bought, so the name itself tells you which era of work is on it.
A storage policy a one-person business can actually maintain.
This is where you hold all of your active footage.