Where’s the best place to start?

I’ve seen many a post asking for “best” settings to “set and forget”, but the prevailing wisdom seems to be that it’s not that simple. I’ve got a 16TB drive that’s close to full with my rips from 4Ks, Blu-rays, and DVDs with more that I’d like to digitize. The old adage of “just buy more storage”is not as simple as it used to be.

My question to you is this: which resources (and helpful tips/tricks!) were particularly helpful to you to learn the art of the remux and the re-encode? And follow-up question, what should I focus on first to bring the overall storage utilization down?

I don’t necessarily need a 90% reduction for everything in my library. If I can use like 30-40% less space across my drive while maintaining as much of the visual quality as possible, that’s probably plenty for what I’m currently trying to achieve. Looking to convert to AV1 for efficiency and to utilize that grain synthesis feature I keep hearing about.