Honestly? Don't do the whole switch, or even a big switch from a few services to another.

Start small. Very small. Try doing just one service you rely on, like your images or music. Immich just announced their first stable release. I use navidrome for my music. Make sure to test these on a copy of your data, not your actual data.

Once you've got one service working as you want it to do, then you can try your hand at another service. This way, you don't get stuck trying to do everything all at once.

It may be worth considering how much (if any) you want to spend at the start, too. That'll inform your next immediate task; setting up basic backups for your data. A spare drive is a good start, but it may be worth keeping another one at your parents house, or similar.