Every once in a while, I get lucky enough to get tapped on the shoulder by an art director, asking for a special promotional image. At times like those, all you can do is allow for at least double the usual completion time, and put in a lot of time sketching, composing, color concepting, and just plain nose to the grindstone refining. When you think your done, go back and work some more. Thats how you do an image thats worth showing itself as the face of a game thats bigger then any individual artist.
There's always a bit of the unknown outcome in any creative business, and illustration probably more than most. Sometimes it turns out good, and sometimes not. The only way to manage that random quality is to put in the time necessary to correct any problems that keep the image from being as good as it can be.
Now that I've commented on the philosophy at work here, let me also say that those branches were a lot of fun to draw. And thats why there's so damn many of them. I'd like to say there's some kind of artistic theory at work, but it's just that I like drawing branches. Sometimes thats how art works too.