Very often, writing competitions or just regular submissions require a certain word count ranging from 250 to 25 000 words. I find it very hard to write to/with.
How do you cope with this? Do you just write ad lib and edit down to e.g. 500 or do you aim for that 500 from the start?
I do both so that I can pace the story evenly. I don't want to be moving along and all of the sudden think "Crap, I have to end this in half a page." Since most stories have a sort of three act structure, even in miniature, I know I have essentially a third of the word count to set things up, a third to complicate things, and a third to work them out. I plan on losing about 10 percent in editting.
Normally, though, I write the story and then search for a market that fits it. My natural pacing, as of late, seems to be right around 2500 words. The biggest thing is to stick to the word count that is listed. A lot of times, they request certain word counts for good reasons related to formatting or logistics.
If you miss the mark by quite a bit, you can always find a different market for it later.