To make post-Cataclysm WOW GOLD any darker than it is.
Since I'm only a fanfic writer, I'm not sure if I'm really qualified to give advice, but I do think that those with an interest in writing traditional fantasy should also look outside of the genre for inspiration. Certainly there's nothing wrong with traditional fantasy, but having a wider frame of reference is never a bad thing. This is true for any creative medium.
Certain chapters are shockingly dark. Was there ever anything that made you sit back and wonder if things were getting too ugly? Or did you see it as the logical result of a world where a lot of really horrible things happen?
It's funny that you asked this, since I was recently on the forum saying that I didn't think it necessary or desirable for Blizzard to make post-Cataclysm WOW GOLD any darker than it is. Maybe I need to pay more attention to what I write?
In some cases, the darker aspects of Travels are the result of my attempts to take a more realistic (at least, realistic as I understand it) look at the setting. This is a world fraught with violent conflict, and there's going to be a lot of fallout from that: Famine, forced relocations, and poverty (all of which which Blizzard touches on in Cataclysm). These aren't necessarily problems that can be solved by sword or spell either.