The thing is for this server is stay alive, communication between the owners and the players is a must. Of course advertisement is a factor but prioritizing to have a solid community is a good foundation. We can achieve that by hosting game and forum events that players can enjoy. Also, making the game more user friendly is a main factor too.
I came from another private MU server and played different servers as well the first thing that I noticed in this server is that I don't know where the heck will I go. I have no idea where the NPC that contains this item can be bought, I have no idea where the mobs that I needed to kill was placed. In short, there's no guide at all. Most of the private servers, I don't know once you're there you know what to do but here? I'm fcking clueless. Making a guide for new players will be a great help in this community.
In connection to the admin's busy real-life sched, I suggest to hire more staffs to monitor or manage certain part of the server. Being an Administrator doesn't mean you'll do all the job to make the server alive and balanced. They can assign someone to go in-game and do rounds, conduct in-game events or at least communicate with the players.