If you're looking for authors that actually interact with your work and you with theirs for mutual support, I have this rules:
- Watch that their sub number is around the same or lower than yours.
- That they work in the same genre as you.
- Check the counters in their profile if you can, if they show they Like and Comment on other people works, that person worths it. If the account is new and they just started, put some faith on them, sub and check again in some months if you see they're still not interacting with you.
- Interact with their work as often as you can, so they acknowledge your existence.
- If you see you've been subbed to someone for some months, interacting with their stuff, and you don't receive response of any kind, it's possible that person ignores comments or simply don't respond to them. Check their profile, this kind of people have almost no interaction in their counters and an empty or almost empty library. Unsub that person and find other people to support.
Now, this doesn't mean you only sub under this rules every time, you can also sub to stuff you like as a consumer. But in any other cases, confront it in a "creators supporting each other" way.