I've been running a server for a few years and the most important thing I can tell you is build a community of likeminded people. Hold on to the players you do get.
It all starts with the people. Without the people, the server is an empty boat in a sea filled with other vessels. Not saying you have to bend over backwards for them, but keeping them happy is important. When I started my server, I had no intention on a big server with a bunch of players. Just started out as something fun to do with some friends. After a bit of advertising (keeping the server page here on PMC bumped and setting up votifier) people started coming and staying because they liked the atmosphere. I guess the best way for me to put it is you get out of it what you put into it if you play your cards right.