Bascially you have a few choices to make as follows:
Type of Server
Judgement of Blood (JOB) - this is the large style maps, older interface and not as many magics, no daily quests (though some may have programmed around this), ingame email and so forth.
Prelude to War / 3G - This is more in line with the Offical Servers and features pretty much everything you expect.
Exp of Server
This ranges from 2/3x Server to some wild numbers such as 60, 62 & 1000x Exp, if you want a long term server then of course go for the lower end of the scale, if you fancy playing killing a mob and going up 10 levels - then the higher ones will attract you.
Do No expect to see the Latest Magics, All the quests working and so forth just yet, this is after all Private Servers not Offical !!