Commitment
Although it seems as if the reason so many servers go offline is because of lack of players, the underlying reason is because the server owner becomes demoralized or loses passion. The owners that succeed are the ones with laser focus and determination to grow and make a good server. Starting a server is terribly time consuming and very difficult. It eats up most of your free time, especially when you are trying to get it to grow. However, you can get surprisingly far just by not giving up at the start. Building a community takes time and effort, but in the end it is worth it.
Staff
There is one common feature to any successful Minecraft server, and that is the staff. The staff team is without a doubt fundamental to the server’s success, but be aware that they can also bring a server down. With this double edged sword in mind, selecting staff members turns into a tricky task. I’ll try to simplify what factors I take into consideration.
The staff serves three purposes. The most important is to help delegate the server tasks from the owner to the staff. When I was starting my server I didn’t have a single moderator until I was hitting two hundred players; while I managed to survive that long I definitely don’t recommend it, as I was spending practically all of my free time dealing with tedious but necessary tasks. Forming a staff team took a lot of work off my back and I suddenly had time to start adding new features. A staff team is practically inevitable if you want to scale your server effectively.
Following this, staff can give you insights into the server that you may have skipped over. They should have a clear way to communicate ideas and events to you. Too many servers give staff the job of punishing hackers and expect them to behave cordially; this is a recipe for disaster. While punishing hackers should be something they do, another focus should be on asking players how to improve the server and actually working on improving it (whether or not they first need to get your approval is up to you).
Another role of staff is to help support the community. Staff need to be charismatic and need to get along with the community. Fostering the community once again comes into play except in this case the staff can be entirely hands on. Helping new players (if they want the help) is usually done by staff, although I recommend the owner to do it time to time. Give staff the freedom to chat with players but remember that the staff needs to be the better person. Engaging in heated arguments should never happen. Naturally, promoting staff that have long feuds with certain players tends to be problematic.
To add onto these three you may want to look into selecting staff that have a burning passion for your server. You can feed off of their passion and they can feed off of your passion; as long as your communication is stellar this practically eliminates the main cause of dead servers – demoralization.
As for management, there are different types of managing styles – hands on and hands off. Regardless of your choice, communication is very important. I recommend using Skype, Slack or Email. These tools radically decrease miscommunication and help make your life as the owner/manager easier.
The role of the owner is to manage the staff. This is basically to know your goals and to motivate staff to achieve those goals by a specific time. You should always have an objective to focus on, whether it is to improve the server, make a new gamemode or to better the experience for new players. Regardless, your top goal should be to improve growth.