Start installing apps from zap.store or obtanium rather than Google store. Much more convenient than downloading APK from somewhere.

Use Amber to generate/store your secret key on your mobile device.

Login to Amethyst with Amber. Or use Primal, but only if it allows login with Amber (did not since a while ago.

Amber, Amethyst and Primal are available form zap.store.

Amber is also on F-Droid, not sure about the other apps.

Also not sure what's a nice and easy Nostr Relay to install on a computer or a Raspberry as I've not explored the options yet.