> I mean I've got lots of books on OTP. But if i'm building a daemon which reads off a queue and talks to some databases - where are some patterns I can follow?

This is a fair point, even in Erlang land. There are a zillion things encouraging you to "let it crash" and far fewer going beyond that.

One thing that doesn't get mentioned often enough is a circuit-breaker like fuse: https://github.com/jlouis/fuse

This also has some more advanced topics:

https://www.erlang-in-anger.com/