The most successful servers I've ever hosted are ones where the initial activity is not dependent on server popularity. In my case, a 'maze world' 2 years ago got 16 people (never had that many since) and my recent Mini Empires server hit 11 at one point. All TDMs I've ever hosted take forever to get 1 person to come, and unless you get 3 or 4 it's no fun and you might as well join someone else's server. After that it's a lag-fest influx of connection requests.
Alternatively, you can say 'Free Admin' which guarantees a few mindless noobs will come, and then remove that tag when you have 5 people or so. Of course, manual admin only, and you can always de-admin for no apparent reason ;)
