Apps: SSO via Authentik where I can, unique user/pass combo via Bitwarden where I can't (or, more realistically, don't want to).
General infra: Unique RSA keys, sometimes Ed25519
Core infra: Yubikey
This is overkill for most, but I'm a systems engineer with a homelab, so it works well for me.
If you're wanting to practice good security hygiene, the bare minimum would be using unique cred pairs (or at least unique passwords) per app/service, auto-filled via a proper password manager with a browser extension (like KeePassXC or Bitwarden).
Edit: On the network side, if your goal is to just do some basic internal self-hosting, there's nothing wrong with keeping your topo mostly flat (with the exception of a separate VLAN for IoT, if applicable). Outside of that, making good use of firewalls will help you keep things pretty tight. The networking rabbit hole is a deep one, not always worth the dive unless you're truly wanting to learn for the sake of a cert/job/etc.
I'm just shocked at the uninspired name choice.
Sleazy Yeezy would have been hilarious.