You can find a lot of guides here,on other forums/sites and on youtube too about how to create your own server!
About my personal experience?
It's not so hard if you want just to see how it is to be admin,to make the server,to edit items,etc and i will recomend you L2J-Frozen pack it's the most popular interlude client and it's really good!
If you just want to open a server for fun you can also find some ready packs of servers and you will have just to create your database and some more fixes on configs and you will have your own server in some minutes