1. Have an overall structure of what you want your story to take the reader. My brainstorming process usually begins with an idea; in the case of Dark as Night, it is sorrow, patience, and vengeance. I then will write down very quick notes about how I want the story to proceed; usually just a line or two which I will later replace with several paragraphs. This lets me know where the story is going so I don't get halfway through the story-telling process only to realize that there is no real reason for the Protoss to be attacking the Terran at all.
2. Drawing. I will usually draw (very terribly I might add) a quick sketch of what I want to explain to the reader. Dark as Night started as the back of a Dark Templar standing on a cliff, overlooking a Terran base in a valley, with several observers in the air. From this I was able to expound on the scenery, atmosphere, lighting, and mood, because I had something to anchor my imagination onto.
3. Research. I was amazed about how many things have been written about Dark Templars. I was able to look through the many Tribes, select one that interested me the most, and expound on the characters personality through it. Seriously, research truly boosts the creative thought process.
4. Revision. I will usually write a brief skeleton of my story to begin with, and will go over it repeatedly until it has been fleshed out and I'm pleased with it. Every time I read my previous writings, I always find better ways to word sentences or describe feelings. Reading and changing my writing over and over really helps it to become much more deep and meaningful.
Anyway, those are for of the tips I have for you guys. I'd like to know some of your strategies when it comes to writing, and will be happy to share more as I can come up with them. Best wishes to your writing! :)