Well, by choosing this over Write a Major MMORPG, you've shown that you're aware of your limitations. This is good. It takes a huge team of designers and a huge budget to make something on the scale of World of Warcraft, and if you don't have the team (or the budget), it's better you set your sights on something you have a chance of completing. This page, then, will help you figure out just what you're capable of. We'll stick to the tropes and advice that work with a low-budget, low-key, probably 2-dimensional MMO, and get you where you need to be.