1) Format it with a popular format like Team Deathmatch and don't enable any of the expansions, as you'll exclude everyone who hasn't bought them.
2) Get everyone
in your clan to seed (start up) the server every day
. Players tend to want to play servers that are already have the action rolling. They rarely will go into a server with only 6-8 people. It's just not as much fun and they'll usually just go wait in a queue for a full server that's already going. Also, once the server is up and running, keep spamming in chat to ask people to add you to their favorites list. After you've been doing this for a while, you'll find that the server will start to seed itself with regulars when the action slows down late at night.
3) If after a while it doesn't seem to be working, save your money and don't renew the server. This is good advice from someone who is already renting one. The problem is that there are simply too many
servers as it is and not enough players to fill them all.
*Also, try to police your server against cheaters and people using abusive or racist language. The lowlifes might think it's funny but the type of player you want coming back won't think so and that will be the last you see of them.