If you want more people to show up and you don't mind if they're just random folks interested in rationality but not familiar with less wrong, you could try making a meetup.com group to advertise your meetups there–there seem to be a fair number of people who browse that site looking for meetups to attend.
Thanks for recommending this site. I found a quantified self meetup that looks interesting in itself and may possibly be a place to recruit for our fledgling rationality meetups in brussels
I think we need to have more discussion of meetup tactics on LW. At my local meetup, we've been feeling a bit lost about what works best, so I hereby propose that we have semi-regular meetup tactics discussions like the open and quotes threads.
So here's a few questions to start us off: