My advice? Have a solid idea of what you want to make. Plot, background, species available, classes, how groups would work, character customization, etc. Make plenty of concepts, write down ideas and whatnot.
And I'm not trying to be mean here, but- if you have no game design knowledge yourself(be it programming, 3d design, etc), then learn it first before ever attempting to start your own game community. Don't ever try something large-scale all on your own without knowledge, and even with a team- the leader needs to be able to work on the game as well.
Trust me, I made the mistake of starting a game when I was only 13, with no knowledge of game design at all or even how to properly run a website. It caused a lot of issues- thankfully, that same game is doing well now, 3 years later, but it was a very hard start and full of conflict and setbacks.
You need to be prepared to dedicate yourself to this. All too many games have been started, only to be abandoned- and that's really disappointing. Before you even advertise at all, decide: Are you really going to do this? Is this what you want to do? Are you going to stick to it, even if it gets difficult?
Another bit of advice: Don't advertise publically for a memberbase until you have at least a small team of designers working with you, and SOMETHING to show. A model, a map, GUI, a start screen- anything. Just show something.
Second: Don't be afraid of criticism. To be the head of a design team, you need to be able to handle stress, criticism, etc., because you're going to get it and it can't be avoided. Listen to what the users have to say- don't just block them out. It only makes things worse.
Adding onto that- one sort of criticism you might get is how something for the game looks. Not everyone is going to be all, "Oh, yeah, that's awesome! I love it!" if your character model looks like a blob or is heavily anatomically incorrect. You need to be prepared for this and I'm sorry to say, and sorry if this comes off rude, but no one will really want to play a game in which the models don't even look like the animals they're supposed to represent. Highly low-poly player character models should be avoided- though ultra high-poly models aren't great either as they cause lag. Medium to low-poly is best- keeping the shape, detail, and etc. of the animal without ruining its quality or making it lag everything. Textures help with the more detailed stuff such as muscle, scales, or whatnot.
In general, it's just best to only try and start up a game if you really know what you're doing.