With that being said, a countdown in Otservlist will get you a good amount of players.. But??
1. Your server should stand among those with already great features and mostly updated daily..
1.a For example, if you are trying to make a custom server, make sure you have something archlight doesn't (or improve it) since archlight is just the one with most amount of players in a custom server.
If you are creating some sort of oldschool (either rl or not), you should also provide quality maps and features (quests, sequential items updating)..
Copying from other servers won't help your if you can't prove it's better.
2. Avoid crashes, these are really the main destruction of a server, since players might lose hype just because a server has crashed once..
You can prove that with beta testers (you can get beta tests here in otland.. Just show some screenshots of your server..)
I remember when i hosted last death, some people were just hyped because i showed them off some quite nice features no server ever had.
3. The way players start. Don't make it very competitive. Don't make it noobie or boring tho..
4. Let quests be differnt in strategy, run-get is not good for every quest.
You should try some mazes including logical thinking.
Not every quest should have a boss.
Make some quests require amount of players with respect to your base online players.
5. Your website layout is quite important.
Screenshots/gallery is a very important interface as players get to know what the server really has to show off.
6. Make some challenging quests, tasks.. Collecting/killing tasks are good, but some tasks should also include upgrading items, travelling to long places to get a unique item.. Talk with some npcs.. Do your magic (of cource there are a lot of ideas, but i didn't mention them as they are exclusive to my upcoming server)
7. Most importantly, CONTINUES updates and teasers.
While you have already served an update, tell the players about the upcoming features or what they should expect in the few next days/weeks.
Your players will get bored despite any features you have.. They seek new challenges. You should have some creativity.
8. Don't work alone. Get a team of at least 3 (mapper, scripter, spriter).. If your server is big, then you should double that amount.
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Also of these tips mostly require some investment. Those good servers such as shadowcores, medivia, hexara, archlight. Those guys spent a lot of money (and they gained it back), but the moral is that they invested a lot to serve such good quality servers..
Sincerely and best of luck,
Slavi