I seem to remember when I lived back in England, sometime during the mid to late 90's, hearing people mention Dubstep and me just presuming it was some breakaway genre of drum and bass, which was really big at the time.
We did the whole rave/warehouse party thing in the early 90's. I remember being amazed by "Jungle," which in the early days was pretty much dominated by the same speeded up Amen loops with ridiculously loud sub-bass. It was pretty hardcore. Then I guess a more melodic element crept in and people started to call it "Drum And Bass." At some point, I remember going into the drum and bass rooms of parties and hearing a more industrial, disjointed beat that sounded a lot more menacing. I'm pretty sure people were calling it "step," and "Dub" was something else, a sub-genre of reggae. I'm not sure at what point the two went together. But I guess it's a pretty clearly defined genre now.
If I had to come up with some dubstep having never done it before, I suppose I would just immerse myself in the music for a couple of weeks, wrap it around my ears.