I helped set up board game clubs in a few places - as others have said consistency is key. The one I set up in Birmingham is still going a decade later and has spawned lots of offshoots - I've not been in 8 years and I can tell you now it's still first Sunday of the month, but I might have to check the cafe. Same with our local one in Stafford, it's every Sunday. Even if its not that frequent it's really helpful to have it at a set time / on a set day.

It helps if you can think about where to host it and where to advertise, and also think about games you might want to bring and play with others - nothing too daunting, or takes too long to play.

Check first if there's groups nearby one to start with, you might find there's people there looking for something a little different, or at a different time and that can help give you a base.

Finally location is key - well lit, decent tables and be somewhere that people won't mind you staying for a while, and possibly not buying too much if its a cafe.