Lets start this off with, do not spam your server IP/information around. For one, moderators like myself have to remove the spam and or organise it into the correct places and such. Generally, spam doesn't look good either. Yes you've got your IP everywhere but people will look at it and think "Damn spammer."

You can only have one server post per account, this does not mean you should go and make more accounts with the same post, that also gets dealt with by moderators *If you are caught multi accounting, you will be banned and your posts removed*. People often ask how to bump their posts, you can do this by updating the information/post with update logs, however, do not abuse this. Abusing that feature can lead to the post being deleted.

After some negatives, let's go into some good things to do.
Youtube, one of the biggest websites on the internet, use it, make a promotional video, put a link to it in your server posts. Learn how to make it look pretty and interesting. Being different stands out, which in turn will get peoples' attention thus, more chance of them logging into your server and playing. So be different and creative!

As I said, you can only have one server post, but you can also post your server in the forum section dedicated to servers! That will also get attention! Same rules as before though, don't spam with updates and bump your post more than once every 24 hours.

People like pretty things, get a nice picture of your server and use it! Maybe ask someone else to edit/make a picture for you. "A picture is worth a thousand words."