Creating my own world... Options

[redsrock]

I was trying to decide on what NON-TES story I wanted to write next, and it donned on me that I have never actually tried to create my own personal world. So that is what I am going to do, but I need your help. Right now I am clueless as to where I want to go with story. I have the map already drawn out in "Paint", but I don't have a name for the 'world', nor do I have any idea on what the plot should be, or what creatures/species I should have.

Can anyone out there help a writer out? Have any of you all tried to create your own world? If so, what are the DOs and DONTs? What caused you to succeed/fail? I don't mean to sound offensive with the 'fail' part, but obviously there's a reason if you failed, and I want to know what it was so that I don't make the same mistake.

This project is pretty high on my list of things to accomplish right now, so I want to get things right. And even if you haven't tried to create your own world, I would still love to hear your opinions.

[redsrock]

Alright, here is the map. The world is going to be named "Mancia". There are a few things I should tell you:
1. The big white squares with the "C" stands for the continents captitol city.
2. The smaller white circles are the other cities. (I have yet to create villages)
3. Blue streaks and shapes are rivers and/or lakes. Surrounding areas outside of land is of course the ocean.
4. The green "haze" in the middle western continent is jungle. This continent has many of them.
5. Orange streaks are bridges either connecting islands, or connect to land to another pieces of land.
6. Tiny black lines over rivers are small bridges.

Keep in mind this is a rough draft. I have yet to dwelve into anything else, let alone specific names of anythig:

Map (Mancia)