EDIT: This is written not particularly aimed at you btw, I haven't looked at your profile/server.
Don't over complicate it.
You need to appear as a proper server, and not a kid asking people to look at his lego.
This basically means:
- As long as your banner isn't an over-stretched image, obviously stolen content or says stuff like 'pls join', you'll be fine. Keep it simple and to the point, the idea isn't about attracting people its about not scaring people away.
- Depending on your server, the description can pretty much be anything. Again, as long as don't seem like a lonely child looking for friends. Have a look at other servers of your type and see what you like and dislike about their descriptions.
- Having players online. Now whilst I'm not particularly recommending using a fake player plugin, if you have any alts or mates with accounts, get them logged in. Just a few at most really.
- Voting. Depending on your server, I'd mostly recommend focusing completely on one voting site. I personally have a roleplay server, and PMC is the only listing site that only lets you select one category; this rocks for me because usually big networks list themselves as everything and actual roleplay servers get buried. Some EULA-friendly voting rewards are to have a chance to give all players a speed boost for 5 minutes, or some fireworks, money etc etc.
You can learn more by looking at bad servers than good ones. So go looking around for things you don't like, figure out why you don't like it and how it should be improved.
Extra stuff:
- YouTube Trailers videos are NOT worth it unless they're good. A bad trailer will scare away more people than attract.
- Paying for advertisements, eh. Don't lead with this tactic, get a base community first and get past all the other inevitable problems you'll have. Besides from attracting players to join, you will also need to work on getting newbies to stay. If you have the money or have already had your start and looking for a boost, sure why not. (I have no experience with how effective it is).