I would suggest that you write a story, map around that story with quests to gain access to certain places and so on.
On thing to keep in mind is that consider what Cip has done with their map, quests etc etc and try to make it feel similar to it. There should be a point to doing things, it shouldn't be free items, highrates or any bullshit like that. I'm tired of playing OT's where it take a day or two to take level 300. The Ot I've spent over 2½ years developing now I've keept thoose things in mind, and I'll be running it on 1.4x rate and the other rates as on Cip's Tibia. And I've made quests that are far from obvious, which will reward hard to get items, for instance I have a quest which reward you a winged helmet. You will have to figure out alot of riddles (and for one figure out where to start the quest), face monsters and look in the world for hidden clues and clues which may seem to obvious to be part of the quest.