Yes, I'd love help with relays selection and management. I've found nothing.
Discussion
Here’s my pretty old post on relays, but it should help at least to a certain extent: https://habla.news/tony/relays
Voyage (Android only) uses the outbox model so you don't have to worry about selecting relays that cover all your friends.
The hashtags you follow however are fetched from your read relays. Voyage will show you the 50 most popular relays used by your friends, you can choose one of those.