I prefer playing a High Five server with rates 10x 15x 20x (Mid one) no donations for vesper items, no donation for GCM like I saw on many servers this unbalance the server really fast and ppls dont like this.
Lets we say donation for Nobless, Max Level, Change Name-Class, double rates ( Premium Account ) if you put ever donation for GCM let them be high price like 5 euro for 2-3 GCMs... you can put also on donations Soul Crystals up to 16 level, no more.
Instance zones for party: Freya 9 ppls , Tezza 9 Ppls.... this is really interesting and its bringing balance between big clans and normal players..
Balanced classes, like in every server gladiators are making imba damage... almost impossible to kill them after month or so...
Thats my suggestions for now. I hope you will get interest on this project and do a good advertisment for a week or so.
Regards.