It's up to you to experiment with what you think will make people want to join your server. Try to be specific with your title, don't just call it a freebuild, or "do whatever" server, because it just blends in with all the other free build and "do whatever" servers. It also doesn't sound very interesting. :\ And for GOD sakes, don't start being desperate, by asking people to join your server through IRC or putting "Free admin" in your title. That's either annoying, or a disaster waiting to happen.
Really, the key is just patience. There's only so many players to go around to each server, if they even PLAN on going to a server, and you yourself need to come up with something to make yours stand out from the others. People won't all rush to your server by default.