What are you trying to do?
In the business world, this would be your business requirements. Once you have those then you can spec the technical requirements.
Without having a target, you'll just be all over the place.
Start with one thing, get that setup, get management for it in place, backup processes, etc.
Then do the next thing.
Iceberg made a great rec - start with Jellyfin. It's pretty easy, but touches on all sorts of stuff like storage, backups (which media is worth backing up?), etc. Plus it has a high reward - watching what you want, when you want, from almost any device.