What usually attract people:
Polls to see what do draw next
Fetishes
R34 (even clean)
Holidays loods
Memes

I've seen some patreon subscriptions allow patrons to get higher resolution versions than the publicly available ones; practice sketches and other WIPs that the artist doesn't necessarily post and just uses for warmup or to practice certain things; tutorials about a single aspect or piece of work (e.g., drawing hair/fur, etc). Just a few things I've seen from time to time.

Aside from the tutorials, I'm already doing all of that. :/

Sorry man. Wish I had better suggestions to offer. :(

Have you gotten to mess with analytics? It's really helpful to trim the fat!