Need help structuring my system flake (with hm)

Recently a friend of mine saw my config and went something like “ew” upon seeing my structure.
I thought it was good at first, but upon further inspection I can see why it’s kind of unreadable, but I have no idea on how to rewrite it, do you have tips to make a “good” system flake with home manager ?
Or are there any guidelines I can follow somewhere ?
Thank you

I’m haven’t read your config structure, so won’t make any specific comments. But having re-structured mine several times, I think the biggest take-away is to create a structure that you can follow. If you look in “config-a.nix” for an option and find it elsewhere, perhaps it belongs in “config-a.nix”.

All the ways I have tried have been flawed - so just make it work best for you! Personally I have common, desktops, servers and individual “machines” but so much never quite fits so I just choose the file I keep opening…after all that is obviously where it should be!