The secret is attraction, not promotion. In my experience anyway. Teahouse by the numbers:
First 6 months - zero visitors. Zero. As in I sat there by myself for over two hours every single time. It’s worth noting that even the people who had encouraged me to start the teahouse didn’t show.
First guest - stumbled in by accident, thinking that the teahouse was part of another event taking place not too far away. They stayed maybe 5 minutes.
After that there were two more teahouses with zero guests.
First year - counting every visit individually (if someone showed more than once, each is counted separately), the total attendance was less (below a dozen) than what would be a comfortably busy evening now.
Record attendance - it was so busy I lost count at 50. Average attendance, a lot closer to 6. There are a lot more regulars than that. But not everyone makes it every week, of course. So there’s almost always a mix of old friends, people who’ve started coming regularly, and first time visitors.
During all that time I had a forum thread, but didn’t really do any ballyhoo. and, thanks to all the irrelevant threads, often the teahouse thread was out of the top 20 less than 24 hours after bumping it.
I put my effort into a lot of planning and prep throughout the week. On Sundays the teahouse for me behind the scenes runs from 2 pm (two hours minimum prior to start) until about 2 hours after the guests leave. That’s the time for mental prep, getting all the rl settling in out of the way, and being in character before the first guest arrives. Then there’s the debriefing and decompressing afterward. 6-8 hours work every Sunday. Plus however many hours I put in during the week coming up with new menus, creating seasonal mogs, attending other events as a vendor, having conversations regarding teahouse ingame during random encounters both IC & OOC , reminding myself of other people’s storylines and thinking about how the teahouse can contribute to their success, …
TL:DR Figure out an rp thing you want to do, want it strongly enough to dedicate a year of weeks (or equivalent) to creating momentum. Plan to dedicate a minimum of 3 hours OOC for every hour IC. Don’t expect any momentum (event seeming to run itself with an occasional nudge) until you’ve put in over 200 hours sweat equity.
And that’s just to keep a little wayside teahouse going. I can’t even imagine how event organizers manage to find time to play their characters while also fulfilling their responsibilities as hosts who set the tone for the server as a whole.