DO: Max LVL 99, Offlineshop, Easier Start till lvl 35, Optional well thought out Questline, Revised Maps (at leats Map 1 and 2), new Low Level Content between 30- 50, Spend much time balacing the Drops
QOL: Switchbot, PickUp Filter, Pickup Everything, Full Inventory, Invetory for Books, Upstuff etc, standart Teleportring
DONT DO: Bonus adder/switcher available through itemshop, 24hr's waiting time on the biolog quests
This list is by no means exhaustive. These are just a few examples of things you could do better then the current oldschool servers.
It's just my personal opinion about servers which i enjoyed playing in the past. I understand anyone who prefers to play hardcore oldschool servers.
I.m.o. it's the most important thing, which is above all else, to give the player the feeling you have put a lot of work into the server. Suprise the people here and there with some new features etc.
Polish the server to the best of your ability before starting it, and avoid game breaking bugs at all costs.
Maybe you're lucky to have a friend with basic knowledge in photoshop or whatever design program, so you can keep up a good image and presentation of the server/events in the future.
(Everything in the text is based on my personal opinion and experience of the past)
sorry for the bad grammar